I've been reading alot of threads about idle issues and surges. But none of them seem to be what's happening to my mustang. It's surging from about 800 to 1200 rpm give or take. I've checked vaccume and pcv issues and iac and tps and all that mess but nothing seems to change. Besides when I replaced the iac it started surging instead of high idle from the old iac. I don't know what the problem is. The car has a b303 cam and gt40 intake and stock injectors.