Lagging throttle response
 

Have a 1988 GT, 121,000 miles and always ran perfect till recently. Whenever I give it a quick rev it hesitates quite a bit before the engine actually revs up. Also, its noticable when shifting gears, give gas as I let off the clutch and can feel the hesitation. Is this just a symptom of the speed density set up or something else. Any help or advice would be appreciated.

Does your car have a TB or a carburator?

TB? But I do know it's factory EFI. Also, today while exiting the freeway the car just died for no reason. It started right back up no problem and drove fine afterwards. New fuel pump installed last summer.

TB is a throttle body. I was not sure what year stangs stopped showing up with the carburator. I was pretty sure it was earlier than 1988, but not sure.

Anyway, your problem could be caused by lots of different things. But, I would suspect the fuel filter and anything ignition related. I am not really good with these motors unfortunately.

I believe that the last year for a carbed engine was 85. I had a 89 5.0(was first year of the MAF mass airflow sensor) and I had a similar problem occur about 75K. It would happen at no paticular time and go away as quick as it came. I remember many people with similar problems and noone seemed to find a fix. I replaced the plugs, wires, cap and rotor, ignition coil, fuel filter, air filter, and it made no difference. I would say try hooking up a fuel pressure gauge and see what its doing when that happens. Preferably one you could monitor while your driving. I didnt try this on my car at the time.