I had 2 different well known tuners work on my tune. One runs a dyno shop and the other tunes for a living. The first guy gave me a new tune after I put an L76 in place of my 5.3. He adjusted a lot and I was very new with HP Tuners and didn't understand much. He couldn't figure out what was causing this and didnt really try much to fix it, just told me he has seen a bad ECM do this. I got fed up, paid another "good" tuner and still had the same thing. He couldn't figure out the problem. It was like 3 months driving like this and I found it myself. Logged ETC TqMgt and saw "Trans" flash. Looked into the torque management and abuse tables and it was all zeroed out. What kind of tuner does that to a stock trans with a cammed L76?? Unreal.

Truck was fine going forwards, but the second you take it out of drive - either park, neutral or reverse for even a second the truck would lose all throttle upon shifting back into drive. It would start accelerating slowly but then lose everything. I'd be sitting in the middle of traffic not able to move for 10-15 seconds. Had to let right off and slowly accelerate again. Pretty dangerous!

Followed a post in HP Tuners about tuning the 4L60e and it has worked like a charm since. I can tell you I won't ever be paying someone to do a mail order tune again. The ones I had were both very slow - upwards of 2 weeks between updates, and neither could fix this issue. Very pathetic.

Sorry for my rant, still angry and trying to get some money back from the second guy as he literally did nothing positive to my tune and charges $300.