High Idle After Warm Up

I have 1989 bone stock Civic with a D15B1 engine with Dual Point Fuel Injection(DPFI). Once the engine warms up, the idle does not drop; for the ECU will not disengage the Idle Air Control Valve(IACV). The idle will drop to near normal when I unplug the IACV, but that is no way to run my car. I think it might be the coolant temperature sensor; however, I do not know the specified range of resistance it should be within. If any knows this valuable information, it would be very helpful since I am having trouble finding it elsewhere on the internet. Thanks for the help.

Robert

I found some information regarding the coolant temperature sensor which states it should be between 200 - 400 Ohms at operating temperature. The RED/WHT wire is a five volt reference wire, and the GRN/WHT wire is a ground; just in case anybody is interested. So everything checks out which leaves me back at square one. Once again, thanks for the help.

Robert

maybe the oxygen sensor? srry dunt kno 2 much bout cars lol

Fast idle valve, EACV and TPS are always suspects according to my Euro manual on Efi Honda motors.