sounds crazy but i put a h22 in my friends civic and it did the same thing. I tried everything IACV, FITV, map sensor, tps but nothing would work. I read somwhere that if the FITV didn't have enough coolant then it would idle irratically. I tried topping off the coolant and blead the system.......BINGO!!!! idled perfect and havn't had a problem since.

 

Yessir. No/low coolant or air in the engine coolant will cause that to happen every time.

 

Theres absolutley no vacum leaks from what I saw, Im going to do the fitv thing in a few, thanks for all the help !

 

Alright, I replaced the IAC valve, check THOUROGHLY for vacume leaks, checked for any fouled spark plugs, filled up the coolant, And the it still idles like shit. Anything? and im not sure where the FITV is located on a h23, Im geussing its the right under the Throttle body. any helpp!!