I have a craftsman 17.5 hp riding lawnmower that is about 4 years old so it only has about 75 hours total on it. I was cutting the lawn the other day and all of a sudden it started missing (surging) like it was running out of gas ( the tanks is full) or the choke was on. After a few minutes it finally died. I started again and it won't start. If I leave it off for a few minutes it will start/run fine for a few minutes then start to do the same thing and die. I have removed the fuel line fom the carb and it is getting gas and also the spark plug looks in very good shape and oil level is up. Not sure what else this could be. Also, I have never really used the headlights but noticed that when the mower is idling the lights are very dim and as you increase the speed they get brighter. Maybe this is a sign of something. Thanks

 

Your problem could be carburetor related but I would first check the ignition system. Often a defective coil will fail when hot and resume working when cooled down.

Get an in-line spark tester, install it and operate the mower. When the engine quits observe for spark as engine dies or while attempting to start. If no spark, the coil is bad and needs replacing.

Post engine model, type and code when posting back.

Testers like the one in the link below are what I like best. They are easy to see. You may find one at an auto parts store.

Sample tester:
Tool Aid 23900 In-Line Ignition Spark Checker

Ignition System Theory and Testing
How does the Magnetron Ignition System function? How can it be tested?

 

Another cause can be blocked vent in the gas cap. Try running it with the gas cap loose, but not loose enough for it to vibrate off. If that works, then you need to clean the gas cap or replace it.