PLEASE HELP ME FIGURE THIS ONE OUT

I have a 1989 Jeep Cherokee 4.0L. I am having a problem at intial start up.
After my jeep sits for about 3-4 hours it will not start at all. However, when i pull the plug to my Idle air Control Valve (Idle speed motor) it fires up and i can plug it back in and it works just fine. The problem only occurs for the first start up... then i can turn it off and on as many times as i like without unplugging the Idle air control valve.

Any ideas would be greatly appreciated... its been driving me insane.
I also just put a brand new Idle air Control Valve in.

New one on me. I've seen the IAC stick closed, which requires you to work and feather the gas pedal a bit to get it running and then it will often stall out after you release the gas pedal. The seat in the TB for the IAC plunger is also often gummed up, got to clean the seat, when replacing the IAC.

The B+ latch relay parks the IAC in the proper spot for a start.

I'm just guessing here, but if I remember correctly, the IAC has a 12 volt power source (unlike many of the sensors which is 5 volts or so). The injectors are also 12 volt so are all the relays, I haven't got a clue if the power source is common or not. It might be possible a short in the IAC wiring is drawing your 12 volt power source down to the point it is affecting other functions. Maybe unplug the ECU connections and test the IAC wires at the IAC plug to ground. Check real close for rub throughs and burn throughs in the wire between the IAC and the main harness. When your starting, the starter draws down available voltage pretty low, in the whole XJ electrical system.

Just on a hunch, pull a couple of relays and see if the base is covered in green (or blue) stuff. If the surge tank for the cooling system springs a leak it will often piss coolant all over the relays. Coolant is a pretty good conductor and can short out or steal a lot of current from the relays.

My idle speed motor caused a high idle 2500rpm. I removed it cleaned it with brake clean sprayed it with PB blaster and stuck it back in. All done at Crawfords at Tellico and it has worked tine since.

Matt

seen this happen on dodge 318's too, (aka grand cherokee 5.2's) he had probs after he sunk it, ruined one iac installed a new one and it did the same thing, i don't know what he did to fix it though.....