I have a 92 Honda Accord DX with a 5-speed manual transmission for some reason I have replaced idle air control valve I replace the fast idle thermal valve it still surges from 500 rpm up to 2000 rpm what is wrong I have a small crack in my coolant reservoir but as far as I can tell there's no air in the coolant cuz I bled it and there was no air bubbles so what is my problem

 

Well since youre throwing parts at it,replace the air boost valve next, as this can also cause a surging idle......