I have a 95 mustang gt that is pretty much stock. I just got the vehicle about a month ago. The stock mid-pipe rotted out right at the cats so I took this opportunity to upgrade. I switched from the stock catted h-pipe to a Pypes off-road X-pipe. It sounds amazing. I am not sure if the problem I am having is related to this but it started occurring shortly after the pipe swap. My car hesitates under light acceleration and idles very rough as if it is flooded. It backfires excessively at low rpms until I stomp on it. Under hard acceleration the car runs fine. I can smell in the exhaust that the car is running very rich. I just did plugs, wires, cap, rotor, pcv valve, air filter trying to get it to run better but the problem persists. The idiot who did my exhaust used a torch to get the old pipes off the manifold and he did not put the O2 sensors back in the pipes. They are just ziptied up in my engine compartment and there are plugs in my pipes. I believe this to be the culprit of my problems but would that really make a difference seeing how I eliminated my cats anyway? Any thoughts would be greatly appreciated. Thanks!