missing power

this has been getting to me latley. when i first start my car and get in if i kick it the rear tires will get loose after about 5min later or so it will feel like i lost 30 - 40% of all my power. ive had this power loss for some time now.
i noticed if i rev it it takes double the time to get to same rpm. and taking off from a light is very sluggish. if i go WOT until about 15mph or so it will look like im just trying to keep up with traffic

i know my fuel pump is on the way out. im not sure if that would cause such a effect. or i was thinking what are the symptons (sp) of clogged cats?
my vac and boost looks fine. tempature is fine.
but i noticed a sound differance when i have all my power sounds very nice
after the power loss it will sound like a tired v8 just chugging along to get there. kind of like a very tired engine with like 300,000miles

any thoughts will be appricated

Trife - a failing fuel pump can certainly influence power levels. If it can not pump enough fuel to keep up with air supply and demand, the EEC will compensate and the car will slow down. A failing fuel pump can be dangerous, it may promote knock.

Has your gas mileage changed?

Its also possible that you have a vacuum leak or an exhaust restriction. The catalytic converters will glow orange in a worst case scenario if they are clogged.

If you know the fuel pump is bad, I would start by replacing it.

well how it is ill get about 12mpg city. and sometimes when im driving ill get that power back out of nowhere but it will only last for 30seconds maybe. engine runs so much smoother.
when im missing the power i have no throttle response at all really

my exhaust flows freely. and as for vacuum leak i dont think i have one another fellow SCCOA member looked at it and couldnt find one.

im leaning on fuel pump as the problem. but ive never seen a fuel pump do something like this. any other ideas?

I started my car without my MAF sensor connected and it made my car revv slow. I'm sure if I would have drove it like that there would have been a power loss because of the messed up air/fuel ratio. Maybee it's a problem with your MAF sensor.

MAF is good, changed it about a month ago.. i was thinking would o2 sensors going bad do this? im still thinking it might be fuel pump