I have a84 5 speed turbo wagon. Thecar starts and drives fine but about every 30-40 seconds -when idling- therpm will drop for a second and then itwill quicklyrev up to about 1500rpms and then quickly fall back down to normal. It does this 2 or 3 times in a row and then it is fine for30-40 seconds until it does it again. Does not matter if the car is cold or hot. The car is also getting bad mileage (about 12-14mpg around town).

I have replaced the injector seals and the O2 sensor. Could it be the Air Idle Control?

Thanks for the help!

 

When was the last tune up? The throttle body could need cleaning.
Edited/
My 745 had a similar problem with the idle. I did a valve adjustment andnow sheidles pretty flat.

 

Were you also getting bad milage? How do you adjust the AIC?

 

Forget what I said about the IAC, sorry.
Try cleaning the TB. That should fix it (you might have to adjust the idle speed after this).
If it dosen't help then the IAC might need to be cleaned.
If that doesn't help, then the AMM needs to be cleaned or replaced.

When was the last tune up (air filter, spark plugs..ect.)?

 

I did not think the 240 turbo's had an AMM. How exactly do you clean the throttle body?

 

Sorry, thinking about the wrong system again
Undo the intake hoses to the TB, and get a can of TB cleaner spray.
You will need a brush and some shop towels to clean the crap/dirt out of it.
Spray the cleaner and get all the dirt out of it.
Then attach the hoses when done cleaning and start the car.

Tech can assist you futher, since you are already talking with him.