I recently had my tractor serviced but after running for about a half an hour it sputtered out and won't start. It has a full tank of gas, new air filter, new fuel filter with 1' of new fuel line, new battery, and two new spark plugs. It will turn over but never fire. I removed the air filter and sprayed starter fluid in the air intake with no change. My thought is that the carb is gunked up after sitting last season. Any thoughts? And before you suggest I take it to the mechanic who fixed it in the first place, let me stop you there. It was a nightmare to deal with them and I'm finished.

Craftsman Kohler Magnum 18HP Twin
Model # 917250480

Thanks for any help!!