Check the compression, get some new gas without ethonal if you can 91 octane at least. Maybe you got some gas with too much ethonal. Hope you didn't forget to put oil in the gas. Steve

I hate to say it, but it sounds like you did something to them. If they were both running great when you received them from your uncle and now both are having problems one day after you ran them, signs are pointing to operator error.

Check compression as ladylake recommends. 150+ is good. Below that starts to get marginal. I think around 120 you will have problems. Check that you are getting the three things to fire, fuel, air and spark. Something else to do is vac/pressure test to find air leaks. If you ran with an air leak for awhile it would run the saw lean and burn it up.