I have an 88 caprice classic that has had some recent issues that I am not sure what to do about. After car warms up, 2 lights come on: the oil light and what I believe is the choke light as it is shaped like a butterfly valve. I know that other gm models had thes two lights combined. The light usually stays on for city driving and usually goes off at hwy speed. Oil is not low, but overdue for a change. There is no audible knocking, but engine does run rough at stops. Alos, when car is first started, it will hesitate from a stop. Press on gas and it is sluggish for a few secopnds and then gets power. Also, it does diesel when turning car off at certain times, usually when light is on and car is warm from city driving. Does anyone have a diagnosis for isssue?

Try running some fuel system cleaner. See if that helps to eliminate hesitation and dieseling.

The oil/choke light came on in my wagon when it was about to stall and before i cleaned the carb. If running cleaner in it doesnt work rebuild the carb.