My 1990 s2 idle is not holding while I come to a stop. Car is warmed up and at red light engine bounces from 1200-0 rpm. Yes, it’d nearly stall and bounce up. If I don’t keep a foot on the gas, car will stall. At abt 15-20mph, I get no power intermittently. This happened just as I replaced the battery (12.6v now).

Any idea?

 

Check the DME relay.

 

https://www.clarks-garage.com/shop-manual/ts-01.htm

 

Check Throttle Position Sensor (tps) , need ohmmeter to verify it. This went south on my S1. I was able to find a used one, as new they are pricey. I kept the old one cleaned the internals, and it's a working spare . Due to position of this sensor, they can gummed up with oil.

 

Issue resolved. The iCV was fouled. Carb cleaner solved it. The idle would dip when clutch is pressed. AI narrowed it down to icv

tpe and dme relay were replaced but didn’t solve the issue. The plugs were extremely black after 30k mi so changed to ngk platinum.

car runs great now. Thank you all for your input!