I'm going to be completely upfront, this car has a lot of issues.
-Registration is expired. Will not pass smog (see next point)
-Service Engine light is on and flashing
-EVAP and vacuum issues. Purge valve solenoid and EGR valve need replacing. Canister(?) needs cleaning.
-Misfiring (cylinder 6? Oh did I mention it was 6 cylinder. 3.8L V6 engine!)
-Takes multiple goes to start (no clicking)
-Stops if you reverse before driving forward. Sometimes stops while driving forward too.
-Previous issue also wipes OBDII codes so I can't even check if there's anything else I'm missing.
-Potential near future issues with transmission and catalytic converter (latter is probably cooked from the misfiring)
-Potentially blown head gasket (oil leaks, mysterious missing coolant, and murky present coolant)
-Front brakes and rotors need replacing
-Front left hub and bearing assembly needs replacing
-One (at least) tie rod loose
-I think it needs an oil change too but I don't remember
-Also has some cosmetic damage but at this point that's the least of your worries.
But I got new tires somewhat recently!
I don't enjoy working on cars enough to deal with all this but maybe you're a Pontiac super fan and this is how you want to spend your time. I think I've put in more than $1000 between the tires and parts and trying to figure out what's wrong with this thing but feel free to shoot me an offer. Expect to put in hundreds to thousands more 💀