Help My Car Aint Working

[jfireballz]

help me please im 16 just got my first car and it has problems 91 pontiac grand prix

it sounds great when i start it up but when it gets hot it sounds really bad and it smokes during that time cold and hot it sounds like its going to break it dies on hills and i think the fuel injection thing is dirty because it hesitates for a split second when i depress the pedal i already changed the oil and had to replace battery and altenator already and im going insane plz help somebody thanx i know you guys can help .....jonathan

[The Burning Rom]

What motor does the car have in it? Is it setting any trouble codes (IE, does the Service Engine Soon Light Turn on).