318i LOW IDLE THEN STALL.
I've got a 1991 318i, and when the car is warmed up the idle varies from 850 to 500. At 500, the car is shaking horribly but then it goes back up to normal idle which is about 850. The gap in the idle increases the warmer the engine gets, so when it's semi-warm it drops from 800 to 600 but when the engine is all warmed up it goes from 800 to 500'ish and then stalls. It's a weird problem, I got my engine code which was 1218 and it said online it was the Output Stage, Group 1. I have no clue what might be the problem, please reply quick!