1998 Chevy Corvette Idle surge?

I'll need more information to help you.

Is your "Check Engine" light illuminated? If so, then you'll need to scan the computer to get a good direction on where to begin.

Was your computer reprogrammed to compensate for the performance parts? (New Chip) If not, then your computer will no longer be able to calculate the fuel and spark timing demands of your motor. Whenever you change the cam and intake, you're changing the breathing characteristics of your engine. This requires more fuel and a different spark curve.

If your computer has been reprogrammed, then the following can cause a surging idle:
Vacuum leak
Faulty IAC
Faulty Crankshaft position sensor
Secondary ignition problem (Spark plugs/wires/Coil)
Stuck/clogged fuel injector
Failing computer

There are no CELs. The computer was reprogrammed and the car was dyno tuned by the previous owner. I was even given multiple dyno sheets showing how the power increased as the tuning progressed.

The surging ONLY happens once the car warms up to normal temp. And what I thought was strange is that its intermittent, not constant. That makes it more complicated for me.

It's very hard to diagnose what's failing when there's no check engine light, and the problem is intermettent.

The only thing you can do is check the following:
Vacuum leak
Faulty IAC
Faulty Crankshaft position sensor
Secondary ignition problem (Spark plugs/wires/Coil)
Stuck/clogged fuel injector
Failing computer