Ok...42RLE... some of what folks are describing here is called hesitation in shifting back into first gear after stopping. Takes a second to get ready into first gear, and feels like a push forward a bit, when it finally shifts into first gear again, while brakes are on.
OR: You Stop. Then you when you step on gas there is nothing until it lurches forward as it has slept, and then decides to shift first gear, with a bit of a clunk. (now higher rpm engage)
What is the problem? Combination of situations if you ask me. First off had it into dealer, they installed some updated instructions into TCM (torque converter module) (shift points re-learned set differently?)
Obviously this 42RLE aint the brightest kid on the block. (valve body & torque converter)
It acts like a turbo 350 (TH350C)that is a bit low on ****** fluid. (higher pressure required to shift back into first, more fluid needed to fix problem)
SO besides having the dealer do a complete flush,TCM update, here are a few things I have done to improve the shifting on the 42RLE.
Check fluid level when hot in Neutral on level surface. (was at full line by dealer)
ADD: Two bottles of Lubgrad red:
http://www.lubegard.com/~/C-112/LUBEGARD+Automatic+Transmission+Fluid+Protectant
This is a quality friction modifier, and after adding the 2 bottles, (slightly above full now) the 42RLE seems to have improved in it's shifting characteristics.
Cleaned the throttle body & IAC (idle air control) allowing for more responsive rpm control, and keep an eye on your rpm to see as you are stopping that the low rpm was dropping to 550 rpm, like mine was, which may be part of the whole problem. Replacing the IAC may be a good idea and cleaning the ports well, may also assist in maintaining a better rpm.