1977 Toyota Corolla

Hi there, I have a 1977 KE35 SR Coupe with a 4age/t50 transplant and I'm having some problems. I was accelerating the other day and at about 5000rpm it dropped to 3cylinders out of nowhere. There was no evidence like smoke or anything apart from the sudden loss of power and shaking of the car. When it idled afterwards it sounded like a Subaru boxer engine and was very lumpy. I had to get it towed home. Not wanting to risk more damage, this morning I started it up and it sounded like it was back to 4cylinders, after about 60seconds it returned to the lumpy idle I had hear before, it appears cylinder 3 is not working after testing the sparkplugs. Any chance you could offer me some opinions as I am a poor uni student and can't afford multiple mechanics opinions. Thanks!
November 4, 2012.

Check the engine compression and valve clearance for a start.

Nov 4, 2012.