I have a MTD walk behind that runs for about 10 minutes and it seems that after the engine gets hot that it just stalls out and will not restart until the engine is completely cooled. I tune it up each year, the plug is new as well as the full filter inside the tank. This year I did try running a synthetic 50:1 mix through it when I noticed the problem, so I removed it and replaced new mix and gas.....almost seems like its loosing the prime, but unsure. The blower doesn't smoke when running.....it has electric start that I use to first start it......I'm just at a lose, done everything that I can think of.....engine repair isn't my strongest point......thanks for any help you all can offer.