ok need a little advice

Basically I'm going tomorrow to pick up a '92 ZX7 from a guy...

Over the phone he told me he let the gas sit in their all winter with no stabilizer or anything so he said the carb needed to be cleaned.

Now due to the rain I wasn't able to take it out and test ride it today but while running it the idle surged between 3k-4k the entire time and when you got on it the bike actually seemed to be running rich rather than lean (only was their for about 10mins today so didn't have alot of time to really look into everything, which is why its no deal until tomorrow)

So what I'm asking is what all could be causing this, as I'm a complete noob to bikes I know almost nothing. I just want as many opinions as possible so I know where I should be looking first assuming I do pick it up

old gas. Probably fouling out the plugs. Otherwise, you said a specific RPM range, which means jetting, probably the intermediate as you come off the idle circuit is clogged. That's what he means by cleaning out the carb(s).