So my girlfriend's 99 Accord EX 3.0 L v6 with 156k miles on it has been sitting for about 2 years. We put a fresh battery in it and it starts right up but now there's an issue with the idle where it just kind of goes up and down between 1200 and 1800 RPM and just keeps going like that every couple seconds and doesn't stop even after running for a while. It starts to do that about 30 seconds after we start it up. I want to say it's idle air control of some sort but I'm looking for some ideas on what it could be.

 

Google fluctuating idle honda...iacv..idle air control valve

 

Try putting in some coolant. That's what mine does when it's low.

 

Surging idle is common and can be cause by a few different things.
Vacuum leak - check all vacuum hoses and gaskets on the throttle body and attached to the intake manifold
Low Coolant or defective engine coolant temperature sensor (ECT) - Check coolant level, test ECT sensor and wiring
Dirty throttle body, intake air control valve (IACV) fast idle thermal valve (FITV) - Clean and test all of them

 

did you figure out what was causing it