Ok so when I accelerate it goes through all 4 speeds fine, but doesnt do that thing with the torque converter when it unlocks or something so my RPMs are running high. But when I drive a mile down my street to the stop sign, turn it off, count to 5, and start it back up again its just fine. Whats going on here?

 

Torque converter lock up happens as fast as you accelerating. If you drive fast in the high rpm range lock up it can feel like an extra gear or a 5th gear in a 4 speed automatic. If you drive slow in the lower rpm range lock up will look like a tach error, where tach holds a spot while you accelerate for few seconds like, you mentioned, before locking up.

If you know the torque converter is not locking up; you may have a bad solenoid or a bad torque converter lock up clutch.

 

FYI 4L60E common problems / failures | GM Truck Headquarters

 

So youre saying your transmission doesnt go into over drive? If thats the case there should be some codes associated with that. But it can take a couple miles from a cold start before the transmission will go into over drive. So are you sure you just arent giving it enough time?

need a little more detail

 

It goes into Overdrive (pretty sure anyway because I tested it and it ran in higher RPMs with it off). As far as accelerating I do it slowly, I dont floor it. But if I dont turn it off then on at the end of my road it wont unlock the torque converter at all (perhaps the problem??), so at 60 mph I'm running at 2500 rpm. I can tell when it goes into that "5th gear" because my rpms drop about 400 off around 45mph.

I am not getting any codes from it, hope this info helps.

Thanks