Just completed a R&R engine swap in my mother in law's 98 accord lx j30a1 v6 (auto trans).
Since getting the replacement engine in and running, it has had an erratic idle revving between 1,100 and 2,250 rpm no load. It holds about 1300 rpm in gear but wants to pull thru the brakes, it is constantly under power. I have gone thru and replaced intake and throttle body gaskets. I've checked visually for cracked vacuum hoses and have come up empty handed. I'm running out of patience with this car, and at the same time I am trying to avoid them having to take it to a dealer and pay a huge bill, for something I may be overlooking in my frustration. And there is NO check engine light or stored codes present.

 

T t t

 

Could it be a throttle position sensor?

 

Got it healed up and running smooth yesterday. Apparently during the course of the engine swap, the IACV moved past it's range of motion and got stuck. Pulled it, cleaned it, wd-40, reinstalled it and it's now running like a champ.

 

Way to go,glad you found it.