[L Oliver]

you didnt say what size motor you have beause if you have a 3.3 v6 and installed a transmission from a 3.0 the extra power could be putting your trans into limp home mode or you installed a tcm from a 3.3 into your 3.0 trans that would explain the bigger heat sink. I'm sorry I cant be much more help but you could check with a junkyard that carries that sort of stuff and could locate the exact same tcm using your vin number