I have a 19.5 hp sears tractor. Last year it didn't run well, so same this year. I changed the spark plugs, air filter, oil, fuel filter, took apart carb and cleaned all the goop out. I checked the fuel pump, but cannot tell if it really works, but I do have vacuum at the base of it.

The mower runs, but only on full choke, as soon as you change the choke it dies. On full choke you can move the tractor, but after a few feet it starts to sputter, and either dies, or just catches itself and does it again.

I was thinking fuel pump replacement, but should I check anything else? I don't know what else it could be.
Thanks
tp1

Fuel pumps NEVER go out. Have you rebuilt and boiled the carb in a solution? Have you replaced the fuel filter.

I have had machines run when the pump was removed from the system. Try gravity feeding the carb with a reserve fuel tank to satisfy your interest.

Don

Are you using fresh gas?

This was a problem from last year, used fresh gas last year, put Stabilizeer and topped off the tank at the end of last season and ran for a few minutes when put into storage. I also added a bottle of carb cleaner/fuel injector cleaner to the tank this year after having the problems.
I think the issue must be in the carb. I plan on taking it all apart again, and really being meticulous this time. I was thinking as I ride it, when I hit any hill in my yard, it immediately stalls out, which I just thought must be a sticky float valve. Would you agree?

No, a fuel starve will cause you to loose power on hills and probably won't be a sticky float. The fuel stabilizer is a good idea but whem faced with a fuel starve ALWAYS start with NEW fuel. It could be a dirty barb in that scenario you would need to remove jets and clean well.
Don