I was a tech at a large city's fleet management service center. I had access to Ford's TSBs. I have a 93 F-150 with the 4.9 I-6 and M5OD standard transmission. I've had it since it was 2 years old and this hesitation had been as issue when I had bought it. Early TSBs about hesitation, mentioned issues to be with the EGR valve and having the correct calibration valve on the engine. I went to Ford and got the correct EGR and it still had the hesitation. I came across a later TSB which is the same as covered here and changed out the throttle body gasket with Ford's updated piece. I still had a slight hesitation. As time and miles accumulated, it was time for some maintenance, so I went ahead and changed the plugs, dist. cap and rotor along with the coil. I use the premium brand of NAPA distributor cap, (actually the higher priced NAPA Echlin brand), because of the fact that it has the longer lasting and better performing brass terminals instead of aluminum terminals that other caps have, including Motorcraft. I did the minor tune up, this time I had 80,000 plus miles on the same original engine. It never has burned oil and at 80,000 miles, I was still living with the hesitation. I got sick of fighting the issue and just considered it as it being the so called, "Nature of the Beast". One day it came to me to change the plug wires, as it had been a while. I had been reading about the differences in plug wires in one of the Hot Rod magazines, so I got rid of the OEM stock style wires and made myself a custom, high performance set for the truck. You can't get pre-made high performance ignition wire sets for the 4.9 Ford I-6. Nobody makes them. I used the MSD 8mm wire wound type supression wires that have a much lower resistance per foot than any off the shelf sets including Motorcraft or any one else for that matter. I bought the wire in a bulk coil from Summit Racing along with the correct type of MSD terminals and boots plus a small terminal crimping tool made by MSD. In total the parts and crimping tool cost was very reasonable when compared with the price of those garbage pre-made sets. These low resistance wire wound wires are what are normally used for high performance ignitions. I made the new set and installed them. Presto! the hesitation was gone and hasn't returned after putting 60,000 miles on this wire set. I gapped the plugs to the conservative side of the factory spec and used regular copper element Motorcraft plugs. I hope that this may help someone out if they have tried the throttle body gasket replacement, (Which I do recommend), and may still have an issue with hesitation. The off the shelf ignition wires have a tremendous amount of resistance when compared with the wire wound performance type. I'm talking about something like 1000 ohms per foot vs. 75 ohms per foot. Another thing that some folks may find confusing is the difference between a sensor and a sender. A sensor sends information to the engine's computer and will have an effect on the engine's operation. A sender only sends information to the gauges and doesn't effect the engine's performance. It just delivers info indicating an engine's operating condition or the amount of fuel in the fuel tank. I found that if your 4.9 I-6 starts and then dies only to immediately restart and run normally after it has been driven for a period of time, then restarted, you may consider that the electric fuel pump is starting to show signs of failure soon. If the fuel filter needs changing, do so, but in most cases the fuel pump is starting to show it's age. I know that this was a long post, but I hope that it may be of help to some folks. These old inline sixes were originally designed for industrial purposes and have a good reputation for powering generators, irrigation pumps and industrial equipment of various types, world wide and their high nickel iron blocks will resist wear for many many operating hours and miles. The fact that they're so durable keeps me from getting another truck. Good luck to all.

I have changed everything and still have this problem, I just cannot understand why it is falling on its face when I go to give it gas

I have a 1994 f150 4.9L engine. I was changing the throttle body gasket which was really bad. I noticed just inside the intake manifold was lots of soot build up. I started scraping it out to clean it up a bit. about an inch inside the intake manifold where the throttle body bolts on there is a port that goes from one side to the other. it was so badly clogged at first i couldn't tell a hole was there. I took a 90 degree flat head screw driver and started to open up the port. I got it opened up from one side to the other,and the hole is about the size of your little finger. Installed a new throttle body gasket and the truck runs like new. replacing the throttle body gasket would have done very little without opening up this port. I thought this might help anyone who is changing the throttle body gasket to check this out before installing the new gasket.

i got a 1990 f-150 with the 6 cylinder,4.9,,i just watch this video,,i went out there and put the throttle body off,,the gasket,looks bad,,i hope that is what wrong,,this truck is about to drive me crazy,,

I wouldn't remove a throttle body if the base gasket leaked. I would make sure the bolts were tight and then simply rub permatex#2 all around the outside and that will FIX IT. You can always fix a vacuum leak from the outside because it leaks from the outside first to the inside even on intake manifolds!!! Now if you are leaking coolant at your intake you cant fix that because it is a leak from the inside out which has pressure.

it should also be noted that low egr flow on these 4.9L motors will cause hesitation on acceleration. ....alotta times that blasted coffee can will rust out at the bottom leaving a vacuum leak at the egr...my gasket was trashed as well on my throttle body....thanks for the video it helped me out alot

Albeit a few years late here's my thank you for sharing the TSB and related repair, it had a very thoughtful vibe.

thanks man. after chasing vacuum lines spark plugs fuel filters adjusting the timing and replacing the iac valve , this gasket was the culprit.

I had hesitation issues on my1993 f15O 4.9 6 cylinder. I changed plugs and cap and rotor. Then changed the throttle body gasket. Nothing helped. I discovered the problem was the temperature sensor. The temp sensor on the goose neck housing the thermostat sends signal to throttle body. This senior has two wires on it, not one. It's right in plain view and easy to see when standing in front of the vehicle and looking in. There is another temp sensor for gauges and light etc. that has one single wire. The double wire sensor controls air fuel setting when acceleration occurrs. I would have never found the issue except for my radiator hose clamp broke causing the hose to come off the radiator. I repaired the hose and filled up the radiator with coolant. I then had no further issue with the vehicle acceleration and it runs smooth now! So I would check coolant level and make sure system is working correctly. In my case the coolant was low due to the hose leaking slowly over time. The sensor wasn't functioning because of low coolant.

Idle sounds high on the video.

There was nothing wrong with that gasket, but thanks for the demo. These things are very simple to work on.

Thank you so much for your information! My gasket was as you said , wrinkled and broke at top middle of it. My 95 also needed the TPS replaced to fix hesitation.

Awesome thanks for sharing that information I’m new to Ford motors -1994 F-150 5.0 XLT Short bed

Just did this today on my 93 4.9l I6. MUCH better driveability, no more bog/stumble to it. Great video.

Thanks i have a Ford F150 4 speed transmission on my motor buts its the same thing i am doing these pretty soon Thanks for the video

Thank you. Im having the same problem.

I have a idle problem on a 1996 you think could be the same problem?

got a 2005 stx 5 speed.idles fine but going down the road it does okay but climbing up to 50 it acts like spark plugs are wet.already changed fuel filter recently but check engine light came on jiggled some wires now engine light is off still does same thing.

Man thanks so much mine was wrinkled but im having 2 other problems out of mine its jumping when it tries to change gears but i can manually shift it and itll act right till drive and the alternator exiter wire not getting power

thanks for posting this, the gasket failed on mine too. It was a cheap fix.