My MTD yard machine lawn tractor has a has a 16.5 hp Briggs and Stratton motor. Starts easily but will only run in the choke (start) position. Something simple to adjust?

Sounds like trash in the carb, or dirty air filter... try air filter first.

Usually when they need to be choked to run, the carb needs to be taken apart and soaked in a carb solution to remove the varnish. Gas needs to be drained each year at the end of the season or varnish will build up over time. The carb is pretty simple to take apart and clean. Rick