Hello Im new here and I hope someone can help me out with my hesitation/idle issue. OK so I bought a completely stock 88 mustang Lx 5.0 AT ASCMclaren edition about a month ago and it had this hessitation/idle issue that I thought would be a easy fix... man was I wrong! The car was like a barn find as It was owned by a old lady whom passed away and I got it for a great deal at a estate sale. Im estimating that the car sat for a few years cobwebs everywhere. the owner kept evey recipt and service record and the newest one was in 2007 so im assuming it was parked and stored after that. So the issue started out with hessitation when acceleration gradualy from idle to about 2k RPM. after 2k RPM it smooths out and drives normally. at idle it basiclly bounces around at first itll idle fine then the idle dips down to about 500rpm then the car goes all panic mode trying to get the idle back up to normal bounces around then levels out for a second or two then dips down then freaks out etc. now at first this issue only happened after the car was ran for 30 minutes or longer as long as the trips were under a half hour the car runs great, normal idle no hessitation. but now it seems to be getting more worse. It no longer takes a half hour now its like within 10 or 15 min of starting the car. and its getting more violatant with the hessitation and idle going hella crazy. so it is getting progressivly worse. Here is what Ive done to fix the issue that have failed each time... Replaced intake with GT40 (explorer) intake and fuel injectors Both coolant sensors ACT sensor fuel filter fuel pressure regulator fuel pump plugs, cap, rotor, wires, coil, and distributor BBK H-Pipe (no cats) all new vaccum lines Set timing to 10 degrees removed all grounds cleaned suface with grinder. (amazing how ford attached them to painted parts) G3 Alt upgrade w/ upgraded ground wires Ran all computer test and get 11 codes and a all good 9 for the cyl bal test. Removed and cleaned the IAC, EGR, MAF. My question is this with no codes in the computer and all self tests come back good. can a MAF, TPS, etc be bad but the computer still thinks its good? Or as long as the computer has no codes it means all the sensors are good? Any info or ideas whats wrong with my new fox would be great.