what causes this?
 

I notice in my '88GT, when at when I suddenly give it full throttle that the car seems to not pull as hard as it should and then all of a sudden it seems to have a power surge as if a 4 barrel kicked in or something. Is this some kind of fuel problem or what is it? It usually happens below 2500 rpms and hits that power surge around 3000 rpms.
Is it a sign of a failing fuel pump maybe??

Sounds like you could have a bad cylinder, or more likely, an ignition problem. How long has it been since you last tune up?

Is there any backfiring associated with this phenominon? If there is, I would suspect fuel injectors.

I replaced the cap and rotor and changed the plugs last summer. I doubt it wouls be a bad cylinder because all the plugs were a nice tan color. It has done that since I bought the car a year ago. I was thinking maybe the fuel filter needs changed or something along those lines. Maybe it's just the engine reaching it's power band. I just thought it should be a smoother power curve with FI engines. This is my first FI mustang. I'm sure it could use a fuel filter change and new plug wires.

mine does that 2
u can feel it wehen it hits the powerband

I was just thinking of that tonight, it kinda seems like i have a race cam in it, cuz it waits till a certain rpm then pulls like a mofo, the h.o. cam has a powerband 2500+ i think, especially after my h-pipe install, but my car is completely tuned up, and does that too, if it was fuel it would starve on the topend, not down low, having some steeper rear gears would probaly help, so you can stay in the powerband, thats why you dont want a Hp cam and no gears, the car would be a dog down low.

FWIW, I have 2.73's, and when you hit about 2000rpm in either third or fourth, it's like I turned the spray on. The power ramp-up between 1700 and 2000 is huge. I think it's just the way the 5.0 works...