Volvo Repair: rough idle, fuel pressure regulator, intake manifold gasket

Question
Regis, I have a 1989 240 wagon with app. 220000 miles. My car has a had a rough idle for about a year now and I haven't been able to find the problem. The car when cold idles around 1500rpm, which seems high but it is smooth. When it gets warm, the idle drops to 700-800 rpm and pulses and shudders, occasionally it dies. It smooths out at 1000 so I have to hold it there with my foot when I sit in traffic. I have had the fuel pressure regulator replaced, and I changed the intake manifold gasket, neither of which were any help. I also have cleaned the flame trap and the inside of the throttle body. I am thinking about going through and replacing the vaccuum lines and cleaning the intake/throttle body again and checking for a stuck idle control valve. Maybe you can point me in the right direction. Thanks, Sean

Answer
I would start with the throttle body there is a special procedure for setting up the throttle body.I would have the throttle cleaned and adjusted properly.it could be a bad idle speed motor.I would have it looked at for a proper diagnosis.where they can check the ignition system on  a scope.

Rege