90Q 20V Engine problems

[Jose Vicente]

Hi all, 

I have a '90 90 Quattro 20V which has been very sluggish lately. Basically
the car runs fine when cold, once it warms up it is very slow. If I keep it
floored to redline it cleans up at around 4500-5000 rpm and then breaks up
and cleans up randomly as if timing was being advanced and retarded but
there is no consistency. The car is freshly tuned up and there is no smoke.
I replaced the Oxy sensor and just about everything else except the knock
sensor. 

Any Ideas or suggestions?

Thank you
Jose

Please reply privately to 
jose-vicente at dsvsamson.com