For me this was the TCC Lockup Valve attached to the wiring harness on my 04 colorado. You'll want to replace the entire harness vs splicing in the the lockup valve as I spliced one in and then the fuse was blowing. Once replacing the entire harness no problems so far. Good luck.

Mine was doing the same thing i didn’t really want to mess with it so i took it somewhere to get it checked saw this video truck did the same exact thing mechanic shop changed the tcc selionid they charged me about 150 to change it now it runs fine

My colorado 3.7L does that I guess I'll have to change the tps and see if it fixes it

I talked a another gentleman and he had the same issue. He changed the TPS and the map sensor and it stopped. so possibly this will help with yours to. when i change mine i will let you know the results

The solution to this problem was a new tcc lockup valve.

I replaced my mass air flow sensor my whole throttle body my TCC solenoid my whole transmission the solenoid was replaced after I already replaced the transmission check the throttle pedal replace the fuel pump the fuel pump sensor the fuel filter and the map sensor and it still does the fluctuation between 30 mph and 50 seems like the faster I go towards 50 it doesn't fluctuate as quickly and last longer than when I'm at 30 with quick fluctuations I'm out of options except for possibly the computer is having problems does not have any codes for the perfectly fine if I drive it rough and hard it shifts perfectly fine only at that same idle speed will cruising between 30 and 50

It sends a pulsed voltage signal to the TCC solenoid. The solenoid moves a valve that sends pressurized fluid to the clutch circuit, engaging the TCC. i hope im not confusing you

i had same thing also did it going into second i assumed it was my trans so got rebuilt but now reading all the comments maybe it was the tcc anyone know about the tcc settings on hp tunner

I've just changed the tcc solenoid, put new trans oil...same problem...I'm thinking about replacing tps..

I have the same problem. I'm gonna try this.

Recently installed a brand new transmission mine still does it also a new throttle position sensor still no fix running out of options anybody wanna help??

how can I be 100% sure that tcc lockup valve is bad, before committing to a 100$ repair, which may or may not solve the problem? there are no error codes.

good night friend .. I have a chevy silverado 1500 lt 4x4. and has the same problem. Do you think that changing this part is going to fix?

My 99 5.3 does the same thing

Did you ever find out the issue with truck. i have a 2002 silverado doing the exact same thing. I was told Throttle Position Sensor. thought I would ask before i purchased a new one. My truck does not throw any codes

I've got a 07 nbs silverado doin the same thing, I thought it was normal with a cam install and bored over but now my transmission is having trouble shifting 1 to 2

Hey man, mine is doing the same thing. What was the problem, it only does it when throttle is at 45.

but if the tcc is bad doesnt it send a code?could the tcc be bad and throw no code?

Sorry for the delay. I actually fixed the problem. There is a TCC selinoid inside the transmission pan attached to the valve body. what it does is tell the transmission to lock the torque converter in overdrive. the part is called torque convertor clutch selinoid. it cost takes $35.00 you will will have to drop the pan so you might as well change the ATF fluid and filter while you are doing it. SO for a $100 you can fix the tranny problem.

Tcc solenoid