Hello Bill:

I'd be inclined to replace the RPM sensor in spite of what others have said. You've replaced or cleaned everything else in that part of the ignition pathway. The sensor runs about $77 USD at sites like alloemvolvoparts.com. I haven't replaced one myself (yet), but it doesn't look all that difficult... Another factor that is worth testing is the torque level on the sensor itself. If it is too loose it may give you wierd signals. Look up the torque spec and redo it! Also, check to see if yours has the white band or the yellow band. The yellow banded sensors are newer and an improved design. When it is having problems and you crank the engine, do you see anything on the tachometer? That is a clue as to the health of the sensor-- no tach action should mean a dead reference sensor.

For what it's worth, I have noted some deterioration in the FI/reference sensor wiring covers on my '89 760GLE (most have suggested that Volvo wiring harness issues were resolved by '88). Have a careful look at your harnesses.

How many miles on your car?

Good luck-- these problems are frustrating!

Herb Goltz, London, Ontario, Canada '89 760GLE w/165K mi