Carb adjustment...well
that doesn't change by itself but readjusting it could fix things. (Back
off the main carb adjustment screw maybe a turn and see if it then runs
sans choke.)


If it's a halfway recent engine, it won't even have any mixture
adjustments. Some of these consumer grade engines won't run right,
brand new. However, the OP said it used to run OK, which means the carb
probably needs a thorough cleanout.