Truck chugs to the beat of the engine from about 5 mph down to 1 mph. Goes away when at a complete stop or popped into neutral. It's worse when I'm heavily loaded or when especially hot. My rpms are pretty high at 750-800 in drive with accessories on.

Transmission recently replaced and the truck did this with old and new tranny.

Any ideas? Thanks in advance!

 

sounds like your converter is not unlocking, does it have the correct flex plate to converter bolts in it? if too long they could have deformed the front of the converter and be causing this. seen it lots on gas rigs, bolts too long or they installed em with a impact. creates a partial lockup

 

hmm, that's kinda what it feels like, like the converter is a little bit engaged. Not sure if the correct bolts were used on the flexplate or not and the shop that did my tranny turned out to be so incredibly crooked they would never tell me, let alone go in there and fix it.

The tranny is still under their warranty, if this really is a tranny thing I'm game for taking it back to them.

Any tests I can run?