idling problems

I have a 1990 accord with 170,000 km and it is standard. I have a weird problem with my idle. When I stop at lights and let the rpm's drop, the idle drops really low and the car fells like it's going to stall. After a few seconds, the idle slowly goes back up to it's normal level.

I though that this might be an egr problem so I cleaned out the intake manifold but the problem persists. Anyone have an idea what the cause might be? I'm thinking it might be a broken vacum line somewhere.

TIA

how low does it go and then what does it go back to? U could try take off the IAC and clean that little screen. The part where the plug plugs into. only 3 bolts holding it. Usually gets dirty every so often. might help.