Volvo: motor accelerates when warm, vacuum leaks, bell crank

Question
I have aquired a 1994 Volvo 850 Turbo, after the engine has warmed up it will accelerate on its own. I can stop at a red light foot on brake not gas, and the RPM's will race upwards of 5000 and drop back to an idle. It will also do this in park or while in motion.With car in park and hood up I can hear fuel purging thru the injectors and then back doen to idle.Were to start? Thanks for any HELP.  

Answer
John,
See if there are any codes in the control unit. Remove the throttle plate and clean it getting all the carbon out of it. Use carb cleaner to clean it out. Make sure that the throttle cable is not to tight and pulling on the bell crank or bobin. Make sure that there are no vacuum leaks at the housing and the intake manifold.