I've got a 1996 Honda Civic hatchback that I let sit in the garage for a long time (6 months mostly without even starting it). Before I did this it didnt have this problem and was running fine. I've now taken to starting the car and actually replaced the battery since that needed to happen (I think the one in there was the original although its been well maintained in its 156K mile history).

The problem is that after I've let it warm up a bit the thing surges. It kind of sounds like a bass groove. It'll rev high and then drop down low. This also occurs when I'm at a stop sign as well, but it'll still drive.

I've checked the air filter thinking that some creatures might have made a home in it, but once I cleaned out some leaves and what not the problem didn't go away.

Why is this happening after I've left it in the garage for so long?

Thanks

 

I have the same car that did the samething 4 me it was the iacv,,idle air control valve its on top or on the side of your throttle body.depends on what motor u have ,,good luk.

 

Cool-

Couple questions:
Why is this doing this after I let it sit for so long?
Did you replace or adjust the IACV? If adjust how so?

Thanks