Surging revs when in neutral and gas on around 2,000/3,000

[seboroth]

So, I was sitting in my car and putting around in it and decided to rev it up a bit, and I was holding the rpms around 2500, and it was surging around 100 above and below what I was trying to hold it at. I wondered if it was because I hadn't timed it sense I replaced the distributor. Or it was a throttle position sensor problem or something else. It does run a bit rich so I figure I should use a timing light sooner or later and adjust the timing. I do have a cold air intake in but other than that its stock. Let me know what you guys think.