Guys, he's talking about a Nat-Asp 1000cc engine, not the 660cc Turbo version. The fault may be a restricted exhaust (choked catalyst or muffler, maybe the mechanic stuffed a rag inside and forgot to take it out), weak compression rings or faulty intake (injector, throttle body etc) or something as simple as a dirty O2 or MAF sensor.
@Poster, this was six years ago, I'm sure you've worked it out by now or sold the car 