Dudsan

Had been sitting up for 6 months or more, changed oil, air filter, plug and gas. Cranks right up as long as you leave choke engauged, but once you disengage, goes dead. If I leave choke on and listen, sounds like a faint grinding noise in motor. Every once in awhile I will hear a thump. A friend said to run premium gas (about 3 tanks) and seafoam and it should work it out. Lol what do you think?