I got a 1990 taurus 3.8, uphills the transmission is slipping, and at stop signs when pressing the gas the engine revs to 2000 rpm and then engages very abruptly. Does it need replacing, or just a fluid change and some kind of adjustment?

Definitely, Won't hurt to give it a fluid & filter change.

Would this Be the first time in What?? Twelve Years !! :devil: lol

Good Luck!!