Just a note on the choke. If you pull the choke most of the way or all the way out, the engine can go from too lean to too rich in 2 seconds.
If you ease the choke out and it gets better, you can move it a little at a time out or in to keep it running. This would tell you the problem was from the carb to the cylinder.
The choke would only help for a second or two if there was no fuel getting to the carb because as soon as the float bowl was empty there is nothing to run on.
The vacuum gauge and timing light can eliminate lots of things fast.
Good luck
