I want to put a 3.1 engine and tranny out of a 96 Corsica in a 91 Lumina with a bad 3.1. What kind of problems if any will I run into making the swap? Thanks.

The 96 engine is OBDII diagnostics, and has a cam position sensor and 2 crank sensors. Your car is OBDI, and only has 1 crank sensor, and no cam sensor. There are so many issues, the swap won't work in any practical sense. It would cost you more in parts then the car will be worth when you're done. Try to find a 90-93 3.1 Grand Prix, Cutlass, Regal, Lumina donor car. The 2.8 engine from a 88-90 will also work. The engine from a Cavalier or Sunbird would work, but they used a 3 speed trans, so unless your's is a 3 speed (rare, most Luminas have overdrive), the trans won't work.