I just bought an '89 Volvo 245 that is idling WAY ROUGH. Runs fine when it's cold....once it gets warmed up the idle becomes rough. Push down on the accelerator and everything seems fine. Pull up to a traffic light, put my foot on the brake pedal and the car starts sputtering and pulsating, I guess. If I take my foot of the brake it will drive on its own in short power bursts. if I put my foot under the accelerator and pull up, the idle smooths out until the next time i come to a stop.
so.... first thing i did was put in a new thermostat b/c the car never seemed to heat up all the way -- the heat blew relatively hot, i guess, but the needle of the temp gauge never went above the 1/4 mark.. so that was replaced. didn't make any difference. all the plugs have been checked, ditto the wires and cap, etc. two mechanics both diagnosed a faulty air mass meter b/c it was running lean and sucking air... one also suggested that I get a new vacuum and breather hose for the flame trap, which had cracked and been mickey mouse siliconed. so i replaced the trap but not the hoses b/c they looked fine. next. i got a new air mass meter which didn 't make any difference . so today, the new diagnosis by my 'mechanic' is that i need a new throttle body. which seems to have been recently replaced -- b/c the gasket looks brand new. which means to me that the previous owner was probably having the same problem and was equally stupefied.
my volvo parts guy told me that it was unlikely that i needed a throttle body... i'...I've been told by various folks that it's one thing and then another by someone else...here's the list

1] temp sending unit that sends the signal to the computer
2] frozen kick down cable
3] tear/hole in the bellows from the air mass to the throttle body
4] throttle body

hope someon can help shed light. i'm nearly broke and want to avoid spending more money unessarily on uneeded parts. any advice would help.