I have the same problem on my 88 prelude. Engine check light ON. Mechanic says it’s my idle air control valve. Took it off, cleaned it, looks like it moves. Put it back on and engine purred at operating temp. Then it started doing it again. One thing that concerned me was the coolant line to/from the iacv. Didn’t get any coolant spilling out when I removed hoses from iacv. Will look at iacv to see if there’s a blockage in the coolant section which may be allowing iacv to get too hot. Any suggestions are welcome!