[larrycar78]

I have a 88 5.0/HO and will be upping the TB from 60 to 65 MM. I was told I will have to increase my idle RPM because of more air flow. Is this true? Thanks for the help. Also, I am putting on tube headers. So, more air in, more gas out. Than ks for the help

[06wrencher]

The size of the throttle body doesn't affect the idle. That is controlled by the idle air control motor. The throttle plate has a hole on it for a little airflow but the idle speed screw is just for a minimum idle speed adjustment.

[larrycar78]

Thanx wrencher, Any idea what would cause the idle to hunt when idling in gear? What happens is once the engine is at operating temp and I put it in gear (AOD) the idle will drop down and surge higher for a couple of revs and then level off. I am using a ECU from a 5 speed and it seem to work fine, also, I removed the EGR valve and cooling lines. I checked the idle control valve by disconnecting it with the engine idling and the rpm dropped way down so it seems to be working o.k. Any suggestions?? Thanks.

[06wrencher]

Probably an idle air control motor going bad. They get jerky and hunt around. They should operate smoothly. Also check for vacuum leaks.

[larrycar78]

I checked for vacuum leaks, everything seems tight. I had cleaned the IAC valve once before with carb cleaner and I'll do it again and see if it makes a difference.