My 95 cavalier seems to be normal when driving around 4 a little while but when i drive non stop 4 about 40 minutes or less it starts to stall when ever i come to a complete stop, then it turns on right away and if i get it going it really doesnt feel normal just to get it goin you have to almost floor it because it feels like it was not getting gas when it is,it doesnt really pick up untill you floor it, sort of like if it was a stick shift car and wasnt getting enough gas so it start to kick thats what it does, when it dies it will stay on forever if it is in Park or in Neutral but as soon as I put it in Reverse or in Drive as soon as i put it in dat gear it dies. I need some help what can this be im thinking its a sensor anyone know what it can be, I took it in to the mechanic and they didnt find anything wrong they said everything was fine. Someone help me....