Engine power cuts out at 2200rpm

[MartinP]

As some of you may have red, in an attempt to solve my annoying stuttering problem that's been bugging me since day one with this car seen here, I tried replacing the injectors and the fuel pump. Both didn't do any difference and I noticed that when I completed the replacement, my engine power started cutting out at around 2200rpm if I stepped on it. If I were a bit more gentle it started occurring at around 2800. The symptoms were stuttering, power cut (very slow acceleration). Rpms below work excellent and engine runs great on idle.
So I switched everything back to the way it was, i.e with my old injectors and fuel pump but the problem has not faded and its driving me mad! What could it be?
Also, I can hear a quiet high pitched sound coming from around the inlet area which makes me believe there's a air leak somewhere. The sound is especially noticable when the engine is cold. The thing is that I've sprayed the whole area with starter gas without detecting a single leak.

Thanks in advance everyone!

MartinP

[MartinP]

I finally solved the damn problem today so I thought I'd post back just incase someone else ends up here. The problem turned out to be the damn fuel pipe between the pump and the filter. While I was tightening the fittings the last time I changed fuel filter I didn't realize that the pipe was twisting at the same time and so it was so twisted that it only let a small amount of fuel come through. Man am I glad that my 480 is up and running again