have a 93 accord. if started when cold will idle at around 2500 rpms for a minute or so. then the idle goes from 1500 to 2500. if started when hot it idles 1500 to 2500 right away. today i let it run for 45 minutes and it started idling fine for maybe 5 or 10 minutes. then it went back to its surging idle.

as stated in a earlier post i cleaned the iacv
adjusted the fiv i think its called that you tighten the top with a screw driver
looked for vacume leaks

someone suggested aybe it is the thermostat. have not replaced it yet. am open to any other suggestions. thank you...KS

 

possibly air pockets in cooling system?

 

i will try to get air out of the cooling system and see if that helps........thanx again

 

also, an idle adjustment screw that is adjusted too far out can cause that, perhaps due to vibration.