When I turn off the car it rolles back and forth for a second but doesn't make a sound, is this gonna cause future problems/am I gonna have to replace something?

Why aren't you using the parking brake?...you are torturing the transmission expecting it to stop the full pull of the car's weight...especially bad on a hill...why the hell aren't you using the parking brake....if you drove stickshift it would be necessary~...yes...will cause problems...like allowing a smoker to take a long trip with you~

Is this the Manual or Auto tranny model?? Either way though, assuming the car is turned off and either in gear (1st, 2nd,etc) in the MT model or Park for the AT model, I'd say the trans. should be looked at....this sounds a bit unusual IMO. Never had this happen in my '87 Fiero GT, to the best of my knowledge.

It was auto. I was looking to buy one. I didn't buy that fiero, is there a fiero that is the best/has least problems?

....not to be a bitter old mechanic, but if you'd USE your parking BRAKE, you'd have a whack at reliable service...hopefully you adhere to the little sticker in the corner of your windshield saying when it's time for an oil change~....we MUST respect our machines and not treat them like crap...at the very least a little windex to see clearly...prior to the accident~

Umm... Ok... I do resect cars, I haven't bought one yet, which is y I'm asked what would be the best and most reliable pontiac fiero to get?