I know next to nothing about the 4R100, but my truck has 85k on it and the tranny shifts PERFECTLY, especially with Mike's tunes running the show.

IMO, the bad reputation PROBABLY comes from the diesel guys. Even in stock form, their engines are harder on the tranny. Then they chip them, probably without or before beefing up the tranny. Throw a few thousand pounds in tow behind that combination, and kaboom.

 

Even with the Mike tune, a Transgo Tugger shift kit will extend the life of the tranny and make it shift firmer w/o messing up the plastic valves. Heat is the biggest issue in those trannies along with a crappy torque converter.

 

Put a 165,000 on our 00 Excursion PSD and that trans was in perfect operating condition when we sold it. Towed 10,000 pounds on a regular basis too. I think people with trans problems do things to them that should not be done. Get a temp gauge and keep it below 130.