Honda question about idle surge

[john]

I am thinking about getting a 95 civic at an auction. Body is in shitty shape but I am just looking for a reliable car. The only problem I have come accross is that it has idle surge. The car idled about 2k when I started it. I reved it slowely to roughly 4k to hear how the engine sounded. When I got off the throttle, the idle surge happend. It seemed to lower (in rpms) when the car started to warm up but it continued to idle surge non the less. I am familliar with how this happens to dsms but not anything else. It usually has to do with a vaccum leak or the ISC going out. What causes this on a honda? Please help ASAP as the auction is tomorrow night. Thanks in advance, John.