940 Low Idle

91 940 SE. (90 760)

I need to set the base idle way to high to get an idle above 600 when in D or R. When hot in P it's up around 1500 rpm and it's 700 rpm in D or R. WTF.

If I set the base idle to 700-800, it idles waaaay to low cold. To the point it will stall.

Replaced FPR with good one. No vac leaks (which would increase idle). Replaced fuel rail. Newish plugs (less than 10k). Ignition components 'seem' ok. ICV motor clicks solidly when in diagnostic mode.

Ideas? Plugs to cold causing poor spark? Would a ICT cause a bad idle cold?

Thanks.

No codes?

Sounds like and IAC valve issue.

Basics:
Clean out the throttle with some paper towels soaked in carb cleaner + maybe a tooth brush. Remove and clean out the IAC valve, bench test it, should snap closed when 12V is applied. One terminal in the electrical connector should show 12V+, ignition on. Make sure the throttle position switch is adjusted so that it clicks just as you open the throttle. I would also adjust the throttle stop such that when you pinch off the IAC hose, the idle only drops just a smidge (this assumes the IAC is working). Also inspect the brake booster hose, once they get really old and hard, they can hide cracks.

Cleaned it. Bench tested it and picked the faster of two I have. Tested it via the obd1 test where it actuates so its getting power. Strange.

TB is clean too. Recently installed the manifold

It does sound like that's supposed to happen when power to the iac is unplugged. I recently had a major hot start and stall issue and because very aquatinted with how that tracts because I had to unplug it to start the car when hot. I'd test power and signal at all temp ranges and gears if you can elevate the rear wheels and make sure it's in spec. Also check the specs on the resistance of the iac you have to make sure they are actually good.

Resistance? Thought it was just voltage on icv motors. Or do you mean ict sensor