I have 1990 Accord Ex. When you start the car idle is around 600. If you rev the engine up then let off of gas rpms drop to about 200-300 and it feels like the car is going to shut off and shakes, but then it slowly climbs back to around 400-500 rpms. I have taken the IACV off and cleaned it with no real results. If you disconnet the wire harness from IACV while the engine is running, engine dies. I heard guys say that when you do this that rpms are just supposed to drop but not die. The PCV is working fine, but currently their is just a regular vacuum hose coming off of it to the intake manifold. Is that line supposed to be a hard line in order top insure proper air flow? I know I might need to adjust idle, which I'm not exactly sure where to do it at, but even if the idle is adjusted, that still doesn't explain why it drops so low after revving then slightly rising higher.

Thanks guys,
Cameron

 

Mine drops a little after I rev it, just for a second tho then it comes back up.

I think your problem would just be solved by adjusting the idle screw and resetting your computer. It's worth a shot. The idle screw on my accord is toward the back the back side of the throttle body, right where the intake meets it. If you were standing on the side of the car, the passenger tire side, the screw is on the top left of the throttle body, facing you.

That's on my 95 accord though. I'm not sure if it is different for your car...it might be. But that screw shouldn't be too hard to find I'd bet it's in the same area as mine.