My accord's rpm revs up to 2k and down to 1300 it keeps doin it until the car gets wamred up. I replaced the idle air control valve, bled antifreeze system, and still it does that. When it warms up to the normal temp, i drove it around and everytime i drove it the temperature gauge goes down to like its barely warmin up, and if i left it alone it warms up and stop the reving but if i drive it the engine goes cold or somethin. I havent replace the o2 sensor for a while, im thinkin its the throttle position sensor cause everytime i unplug it, it stop the reving. and the check engine light came on. Could the o2 sensor be the cause of this. the antifreeze is full, with no air in the system. my choices are to change the o2 sensor and the tps to see if it stops doin this, oh and my fans aint workin, could this also be the t-stat. and could the the t-stat cause the engine to cool itself everytime i drove it? If you guys knows whats wrong with my car hit me thanks.

90 accord with a 96 f22b1 vtec engine.

 

Read my lips..........Diagnose, Diagnose Diagnose,, do not replace unnecessary parts it is a waste of money and do not take wild guesses and hope to get lucky .....

try this,, remove the top cover on the fast idle valve 2 phillip screws,, tighten the inner big valveon the inside ,, it has 2 cuts on each opposite side ,, you need a screwdriver ,, do not overtighten it ,, do it just till it sits, reinstall fast idle cover and try it ..

let us know the outcome ,,

 

If what DH said does not work, you can take the ICV off clean it along with the metal screen that covers it. use Intake cleaner.......