okay so i picked up a 93 banshee today, full bills pipe, bored .50 over, uni filter, ceet cover full skid plates... and the guy told me it needed work, he told me it needed a new wireing harness because the engine is not getting spark. so today i tested it and it was sparking fine and wouldnt run more then 30 secounds and at a low RPMs would just bog. i think its a airleak. i pulled the engine out today to it rebuild it with new seals and gaskets. and a full tune up. i cleaned the frame up really good also. any ideas on what could cause this?