As I was lying in bed two nights ago, unable to get to sleep, I started thinking about the Subaru again. Could it actually be something other than the engine?

I went out yesterday and started it up again, and paid a little more attention to the noises it was making and its mannerisms when stomping on the gas. I let it get up to operating temperature, which it did just fine without blowing up. When the engine is warm, it'll get up to 4,000 RPM before starting to fizzle, but it seems to me now that it's some other problem causing it. Maybe the carburetor, possibly one or more bad plug wires or something wrong in the distributor. I'm not sure I'll even be able to troubleshoot the problem, since I was never good at figuring out an engine that just runs bad. Hopefully a few questions here will point me in the right direction.