Stalling 87 Carrera

My 87 Carrera has stalled on me each of the past two days. At idle on a warm engine the engine revved slightly and then quit. It restarted with no problem. When it quit I saw a puff of smoke. Thanks for any suggestions.

Check the resistance on the head temp sensor. Has a negative coefficient and when hot should read about 80 ohm. When cold, a few megohms. If you have a bad ground on it it would give dme a "cold " res. and enrich the mix, causing the revs to increase. Perhaps also to stall. See the tech write up in this website about replacing this component. A buddys 88 would not run when this sensor failed. Ned