1996 Honda Civic when idoling car reves up and down

I wouldnt know if I would say o2 sensors because they arnt even used at first start up, the engine goes into loop mode and bypasses them.

It could be the map but the map would make it seem like the vehicle was gonna drop so low it will stall then come back up a little bit bellow normall then plumit again.

I would be checking for vaccum leaks and making sure the IAC module is functioning and the throttle body is clean first.

Hi,

I agree with what blackop555 says and also if the idle speed is adjusted too high, it will also cause the problem.

Other items include the fast idle valve which sometimes unscrews itself due to a hardened O ring thus resulting in not being able to close fully and allowing excessive air flow. If the coolant bypass hoses to and from the fast idle valve is clogged, you would also get the problem.