[Zeke's Garage]

Can you hook up a vacuum gauge to the engine while it idles and see if it stays steady, or is fluctuating? Something sounds really odd. The way it revs really slow sounds like retarded timing, but it's tough to tell without putting hands on it. Verify TDC by using the piston, you can't trust an old harmonic balancer, they tend to slip on the rubber ring.
Sounds like more than one thing might be going on here, so also check your spark plugs.. its' really easy to crack the ceramic while handling them and you'll end up with a misfire.

Good luck with it.