OK, back with an update. The guy put my carb on his tractor yesterday and said it ran pretty well, not as strong as his carb, but still very strong. He came back today and put it on my tractor and it was still having issues. I don't know if this is "missing" or what but I took a video when I got home of the behavior.
http://img593.imageshack.us/img593/4444/iw3hdcesgwcthqegfldwsa.mp4
So when the throttle was low it idled rough, in the middle of the throttle range it idled better, and at wide open throttle it was the worst. When you hear this what do you think it is? I asked the tractor guy to pull the distributor and check the timing with a ruler -- he said it was only off a smidge and he corrected it.
So, despite replacing all of these parts, going through the carb again, etc. I drove the tractor out to my barn and it seemed to be doing fine. I was backing up very slowly and it started to stumble, sounded like it was going to stall, and backfired. Then it shut off and I couldn't get it to fire back up. The ammeter was bouncing back and forth like I think it should but I couldn't get it to fire... %$#%$#$#^%^
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Soooooo... I have a theory. Do you remember me mentioning that even with the new alternator the battery wasn't being charged? Is there any chance that I actually have 2 problems going on -- maybe a break or fault in the wire going from the alternator to the battery, so the battery isn't being charged, and then because the tractor is only running from the battery that it if there was a fault in the resistor or some other issue that it would stumble and die? The battery voltage was 12.7 at rest (it's been sitting for a few days). I am running out of options here.
The tractor guy seemed pretty stumped but is going to come by tomorrow free of charge. He thought there was a remote chance it could be the condenser (I will leave my new one for him to install) or a problem with the resistor.
P.S. The panels in front of the barn are there because 1) I didn't get them on permanent mounts before winter and 2) in the near upright position they shed snow.