My check engine light started to come on a few minutes after cold startup, and doesn't go off. I now notice that the engine starts up cold with a slow idle, maybe around 1000 then drops, where it used to start cold at 2000 and drop a few minutes later.
The engine is 2.3L 4 cyl in a '92 Ford Ranger pickup, with 40,000 miles. I just had it checked for smog in June, and it passed. The slow idle at cold start makes me think it might have something to do with a temp sensor. But my knowledge of electronics, altho really good, isn't up to speed on the workings of the newer auto smog controls, etc. Thanks for any help.