tbt

my 87 s4 has an idle surge of between 850 & 950 rpm....it will get more erratic(range-wise) when you ease out on the clutch without accelerating. like when you are easing up in traffic from a stop..or when you are in first gear & letting the idle speed pull the car.....does fine if you accelerate from stop to speed, normally.....vacuum is fine(no leaks).
Tom Taylor

SteveG

Does this happen hot and cold? If for no other reason than it's up front and easy to check, I would start with the Temp II voltages and rule that out.

[edit] As soon as I post, another thread (below) is up again and lots of possiblities for you to check.

https://rennlist.com/forums/928-foru...dle-fixed.html