Fellas:
I am putting years on my life trying to find out whats going on with my 89 Volvo 240. I just picked up another 240 and its in pretty good shape. Because I have several Volvos, I just started messing around with her this week. She has an intermittent problem. I can start her to mover her around the yard with no problem sometimes, but other times as soon as I put her in either drive or reverse and touch the gas(she stumbles and shuts off). Since this happened I replaced the Mass Air Flow Sensor, air filter, and a new fuel pressure regulator. Some days she will start up perfect, and other days she will do this annoying problem. The car has 180k on it. I can raise the rpm's with no problem while the car is in park and nuetral when she is acting up, just not in park or reverse. Have any of you had a similar problem.

This weekend I replaced the in tank pump and the inline fuel filter and all is well.

Try cleaning the throttle body and idle air control valve. Both should be removed and completely cleaned. Get a new gasket for the throttle body and put 12 volts across the idle air control valve to see if it is working.
Also make sure the throttle switch is adjusted properly, check the 700/900 FAQ's for procedures.
Dan

fellas:
I am think my idle air valve is acting up. I swear all yesterday pm i went out and the car was acting up. This am i went out to move it and it was closer to 60 degrees and it started and moved just fine now the temp was colder. Yesterday pm it was closer to 80 degrees when it was bogging down when i placed her in gear. HHHHMMMM

My car did this when I was adjusting the TPS after cleaning my throttle body ad IAC valve. Make sure you set the switch with the throttle pulley disconnected from the butterfly valve linkage, then adjust the linkage accordingly. Might seem obvious, and I sure felt like a ree ree afterwards. It drove me mad for a good hour.

Good luck,

Justin