I have a 1988 Accord LXi. All I did was change to oil over the weekend but now the idle races up to around 2000 rpm's then drops back to 800 or so and then right back up to 2k and back down. Over and over even after the vehicle warns up. It does not stay at either RPM for any length of time, just goes up then down then up. I've looked for a vacuum leak or some hose I might of disconnected but have found none. Any ideas?

 

I'd bet the oil change has nothing to do with this.

First, check the coolant level and be sure the air os out of the system.....yes this will cause these issues.