Yes indeed, I have this issue with a friend truck.
Is a 02 rcsb 4x2 LM7, Cam, heads (Patriot), CAI, 3,42.
I know and he knows OE injectors are on the edge. Some 42 are on the way.
Meanwhile I manage to make it idle great (still a weird issue at starup, and shifting fast to D or R, no brake will hunt idle.) if you let it settle for a sec or two will idle great !
Fuel and Advance are pretty good too.
Now, the 4L60E seems to have life of its own. I started moving the normal thing to make it shift strong and wild with the T/H on. T/H off will have street manners.
Now, when it was "working" shift perfect as commanded. But time to time It just did shifts at low rpms (2500+/-)
We send it to trans shop, and the say it was everything OK.
Then We send it to Dealer, and the say TPS was hanging some, and place a new one.
After that, same issue with gear shifting.
I burn my eyes searching the web for some issue like this, no luck.
So I just went bad, and change ALL tables in the Trans section to Shift as I commanded !!!!!
Took away everything I know that could cause low power mode.
No luck, same thing.
Now, I scan it today, with a trans cfg only to try to find out the evil in it !!
Now here is the interesting part. In the log It shift normal few times, and did the fail few times too.
When normal, "Trans Shift mode" at 100% TPS readed "Normal Shift WOT"
But when the failure appeared I read "Normal Shift" also at 100% TPS
Now, when in failure, you can step into the radiator, and read 100%TPS and will shift at around 2700 rpm ALL GEARS 4th included !!!!!!
No power of course because at that RPM no torque has been build. But entering 4th when in all tables 4th gear must enter when 255 mph are reached !!!! Now that is weird in my book.
This failure comes and go. No apparent relation with temp as you may see in the log. and VSS and TPS(new) are working ok to my sight !
I'll post the log, the cfg file to see it, and my tune.
If anybody can give me some help to find the light at the end of the tunnel, really appreciate it. I'm almost giving down on this one !