Hello AFM members! I have a 1998 mustang gt (stick), sometimes stalled when i tryed to start it, after that it will stay running. However when the car warms up, and i roll up to a red light, and stop, the rpm will drop to 500 rpm, not all the time but sometimes. It also gets a little shakey when at 500 rpm. i bought a new alternator, and a new bettery. (the battery meter would go lower and lower when driving) the new parts only helped with the starting of the engine, but didnt solve my problem with the drop in rpm. before the new parts it would dip 3 times from 750 to 500 then idle normaly, back up to 750. I need some help befor i spend any more money.. im only 18 (no money to waste)! there is NOT a check engine light on!!! Is there any parts i should look at, and or clean? Please help!