2000 Grand Am V6 stalling Ilde issue

Hello people, my grand am has a gnarly idle issue. It stales to turn on and once on it has a very rough idle. When I put the car into drive it stales then just turns off. Drained the heck out of my battery so I was thinking it was an alternator issue but I did a quick test and my alternator seems to be working fine. I did manage to drive my car but once in motion, gears wouldn't shift which has me leading to thinking it can be a transmission issue. Any sort of help will be useful and much appreciated.

Specs:
2000 grand am
3.4L V6 SE model
automatic

how many miles? and have you overheated the engine?

Bad gas ? clogged fuel filter? their are a number off things that could cause these issues.
check for vacuum leaks around the intake.