There are a number of threads on this topic, mostly pointing to the throttle body as the culprit. I had the same problem when I bought my 94 about three months ago. Turns out the problem with mine was low radiator coolant level.
As a first step, I would clean the throttle body really well and also make sure none of the cables are sticking. It is normal for an 80 to idle pretty high at startup although 2500 sounds a little high.