Car developed a stumble till ~2,000 RPM's, New Wires, Plugs, New 02's, Gutted the cat, etc. When rev's it stumbles, however when revved slowly it doesnt. When under load it stumbles and breaks up till 2,000 RPM's then clears out and runs fine. Seems to be detonating some also. Checked the EGR valve, diaphragm doesnt want to move, however disconnected the EGR, plugged the vacuum and car still wont run correctly. Ran some FI cleaner, still no luck. LT4 KM also in the car.
BTW its a 94 Z28 A4 Car

Did you check or replace your Opti-spark
recently ? Also, the gutted cat may be
creating a lean out condition. You may want
to check your intake elbow and Maf for leaks
as well.

The big suspects are the Opti and the EGR.
Make sure they are up to snuff.


Good luck graemlins/thumbsup.gif

Had similar symptoms with my 93's opti. It got progressivly worse. Never threw a code, and after trying a few other things, bit the bullet and replaced it. No problems since. Have you replaced your O2 sensors lately?

yes the oxygen sensors were replaced