i have a 1990 V8 Quattro. i notice that my tactometer seems to have a 'fibrilation' when the car is in park or stopped. it runs around 700 but sometimes drops to 500 then goes back to 700 then up to 850 and so forth. should i be concerned over this? the car has 147.5 k on it and was just in for a major tune-up. sparks and whatever else they do done! please advise

But with that many miles my guess would go to intake hoses/plumbing. Air leaks are often the #1 culprit. If that engine has an idle stabilizer valve, that could require cleaning and or replacement

rob, thanks for the speculation on that. it makes sense and gives me something to go on right now. and if thats the culprit, that is not a major thing to be concerned about is it. i mean having slight 'murmurs' in the rev of the engine isn't going to leave me stranded or take away from the car's performance. i'm a little paranoid with these things. any one else with input please post.

spark plugs (as you said were done)
plug wires
distributor cap & rotor
fuel filter
air filter
MAF?