Zero Turn Mower. I'm stumped.

Glad you got it sorted out RRR... as soon as I see runs better with the choke out it's a fuel issue as choke = less air to get a proper mix with the less than 100% gas coming through the fuel line. I spend 1/2 the Summer every year "fixing" widowed ladies boats on the islands around us at Camp. Separating their water from gas in a 60 ounce booze bottle and then pouring the actual gas back into their tanks. The boat cans leak rain water through the lids while sitting in the boats. Nothing a solo cup cut to fit won't fix, but some are worth spending time on their docks! :)