whenever i put my foot on the gas the revs just don't seem to fly up like they used to, i can still hear the whistle from the turbo and it still kicks in but the car starts to run a little lumpy and the revs just aren't picking up like the should be, i just sit there waiting to feel the pull and for the revs to whizz up but it just dosen't happen (no matter how long i'm on the gas!), the car is def slower, very embarrassing some little fiat coupe managed to keep right behind me today coming off this roundabout and i had the gas floored, flet like i was in a 1.3 encore, not a tuned up rs turbo, something is wrong, any ideas what it could be?

i've recently put a dump valve on, but it won't be this because car was running fine right after it was fitted, the radiator water pipe bust onto the altenator... (for a 2nd time), its after this happened that i actually noticed the problems, could that be something to do with it? i also replaced the plugs and leads, didn't make any difference, i've also been told the dist. cap, throttle and fuel filter need changing by my mate who is a mechanic, to me it just seems like there isn't enough power/throttle/fuel or whatever going into the engine... throttle response is very poor, so my guess is it could be the throttle or some sort of fuel injection/filter/mix? i also noticed a little bit of backfiring today, but don't know if that is related to the problem or not, it was nothing major just happened a couple of times whilst i was pulling up to my home

if you have any idea of what it might be please let me know, thanks