Loss of power at high revs.

[hitork]

I have an av tx5 2.2 non turbo. It has a straight through muffler and a heap of ignition timing advance. When it is reved above about 4500 rpm it looses power rapidly, so rapidly that in the few occasions i have raced it i have shifted at 5000 rpm. I have never reved it above 5500rpm. The loss of power is massive. I have tried changing all filters, high octaine fuel, injector cleaner and nothing has helped. I have a feeling it could be the EGR system, but im not sure how to check it. What could be causing this? If i was to remove the EGR system what sort effect would it have on the motor? Tomorrow im gonna try removing the vaccum advance from the distributor. Your help is greatly appriciated.

[dirty hands]

either loosing compression spark or fuel pressure/flow at those revs ---nonturbo
my guess is valves may be leaking or timing issues

two sites of intrest
http://www.mx6.com /forums

http://z3.invisionfree.com/tx5/index.php?

[hitork]

Well your right in the money with the valves I think. I get a fair bit of black smoke on startup, espically when its very cold and you hold the revs up a bit. Im going to change the valve guide seals or what ever they are called when I change the timing belt which is dew in 1000 kms.