Sounds like something is not lining up. Did the problem acure after these changes. BEWARE : using that belt slip stuff in a can, will build up on the serpentine belt and cause more of a problem. Check your belt for alinement. If the pullies are gummed up, cleaning them could be a PITA .Try Accatone.( HomeDepo ) Read all warnings. Clean all pullies and replace with a new belt. Good Luck !