Strange Idle problem...

[CaelanSeth]

I know there are several posts on idle problesm but I could not find a solution. OK so my car is a high mileage (225,000 miles) 1989 240 auto. Last week it idled fine, if maybe a little low.

I changed my belts a few days ago, while I was at it I sprayed a bunch of cleaner in the throttle body and cleaned the plate.

Put belts back on and everything seemed good, except I noticed the idle was very high when I put it in park or neutral. And when the car gets warm, the idle rapidly bobs up and down from around 1700 to 1200 rpm. I first tried adjusting the screw, it had no effect. I figured the cleaner in the TB pushed a bunch of gunk into the IACV, so I tried cleaning that.

When its in drive it seems ok, except when i let off the gas it seems to drop rpms very quickly, but that coulkd just be my imagination.

I removed the IACV and cleaned it out real well, there was a gasket between it the the TB that broke so I put it back on without it, as many people have said their cars dont have the gasket. Anyways, I wasnt sure where to position the brass screw so i just screwed it in quite a ways, put the valve back on and my idle is worse, now over 2,000 rpms.

I pinched the air regulator hose to see if it would drop, it didn't. Disconnected AIV, but it had no effect. I cannot think of what it could be, except a leak possibly somewhere in my intake, the rubber bellows that connetcs to TB is old and a little cracked, but i dont know and have no idea why it started when I changed the belts... any one have any idea?

[r3v_v3ng3]

check your coolant levelback out the brass screw in the iacvloosen your throttle cable and see if it does anything

[Wc240]

put it in base timing then adjust your iacv and that should do it