'94 cpi throttle body. 4.3 litre.

i've turned over many stones.
high idle. approx. 2500 rpm withOUT load. (in park or neutral) idle is fine in drive, though on ice and snow, i have a lot of spin in the back tires. it wants to go!

i have a code 35, which i believe suggest iac valve.
check engine comes on at a stop, turns off EVERY time at about 40 km/h

i have cleaned iac valve, i have checked vacuum leak as best as i can. i've pulled hoses off, and there is a ton of vacuum. does this mean i probably don't have a vacuum leak?
i had propane around possible vacuum leak areas, and had no surging... is ether a better choice? will air intake cleaner work?

egr valve is apparently of issue, but i don't think that would account for the high idle, as i've never heard of it being the cause of it. (but who knows)

the truck has 430xxxkm on it. i am leaning to replacing the iac valve. anybody know if these things wear out? mechanically that is? apart from just getting dirty?

sorry for such a long post, i've spent so much time on this, and need to make a move. the u joints are not happy with me, i know it.

 

Any thoughts folks?

 

I've read that the pintle in the IAC has to be set in the right spot. I would replace it since you have a code.

 

Thanks for the advice. It sure feels like thats the issue. If i have the valve wires unplugged, truck revs haywire. Like 5000rpm. Clearly this little valve regulates air intake bigtime. Most notably at low speed idle

 

If one turns the key over, but not starting it, will the iac valve pintle move in or out?

 

Has the factory idle set screw been adjusted on the throttle body? Check timing? My experience with EGR was when a replaced a bad one (idle was rough, very low to new one (Idle was very high) couldn't figure it out until I replaced throttle body. That brought me back down to 650. Turns out the set screw was adjusted. You're not supposed to adjust those.

 

Idle screw not been adjusted. How to chexk timing? With a timing light and all that jazz? Idle had not changed with egr sawp or blocking it off completely. Why did u have to rplace the throttle body? Was the throttle slide/flap not closing completely? Man i dont wanna buy a 75 dollar part for no reason (iac valve) anyone know if it is supposed to move when the key is turned to the on position? (When its removed from the throttle body that is, so as to be able to see it)

 

Maybe it would be similar to this.

 

Yes, check it with a light, computer unplugged before you start (single wire is underneath carpet and dash on passenger side. Initial time is what that's called.) Should be 0 degrees if proper. I replaced the throttle body because the factory set screw was altered and there is no real way to ensure it was set back to factory spec. I have a couple of throttle bodies laying around, which means I have a few IAC valves. If you pay shipping I will be glad to send you one.