1986 325e. With vehicle idling in parking lot whilst working on...you guessed it...jumpy temp gauge...it appears engine is "loading up." Went to drive away and considerable black, then blue, then white color exhaust smoke upon initial acceleration. Seems to clear up quickly as I continued down the road. Have had 2 occasions when I shut off vehicle, left it for 10 minutes, returned and attempted to start and engine would not start immediately. Had to floor accelerator pedal and eventually engine started, although had to keep pedad depressed to "clear out" excessive gas richness??? Any thoughts on what would be causing this? Thanks.