Fuel pump & fuel pump relay will start getting faulty/go out on those and cause them to run weakly. You can get Chinese replacements for <$50 combined. Even the cheap Chinese ones will instantly bring it back to life if that’s the issue. Check the fuel delivery system (including in-line filter) before doing anything drastic with motor.

Make sure you’ve got a good charge on the battery & a good connection as well. Check voltage at fuel pump. If you aren’t getting sufficient voltage it will run weak or idle but then die as soon as you give it any throttle

I’m pretty fond of the mules & they aren’t terrible to work on.