I have to chuckle every time one of these threads comes along and there is 15 post on APPS, TPS,and the TC lockup clutch engaging.
These trucks haven't had a TPS since the mechanical systems went away and the APPS on the newer trucks very, very, seldom go bad. They are double wired for inputs and the ECU has the final say about the output. It will smooth the signal until it is way out of synch then go into limp mode. With the throttle closed the APPS is reading zero and has no input to the engine to rev it. If it was reading a signal the engine would never idle down. When an APPS goes far enough out of synch the engine goes to limp mode and defaults to idle.
If anybody thinks its the lockup solenoid engaging go put a lockup switch into the system and engage it. Slowing down with the TC lockup engaged the truck will literally jump off the ground when trying to stop. Going from neutral or park to drive will kill the engine NOW. There is no doubt when it is a lockup solenoid problem.
That said, there are 2 areas in the TC that are problematic especially on a stock TC: lockup apply piston and stator sprag.
The apply piston can warp and leak pressure against it that can at times partially apply the piston. If that happens it will happen all the time and drag all the time.
A biigger and much more frequent problem is the stator sprag locking up when it is not supposed to at an idle or low rpm. What you then have is a no stall converter that is loading the engine while it tries to maintain idle rpm. It won't show up until you go from neutral or park to a gear then it tries to go. The trans will usually work perfectly at cruise and after you get to 35 mph or so. It will also happen intermittently if the sprag does not seize completely.
The 06's have a bigger issue than the other years but it can happen to any of these trucks. The OE TC takes a beating from the TQ.
almost always when the truck wants to pull thru the brakes at an idle in gear, shifts fine once oyur up to speed, and is doggy off the line its time for a new TC.