Picked up a Husqvarna ST324p in excellent condition off FB marketplace for short money. I fully understood I was picking up a big box machine (my previous machine was a Toro PowerShift), but still figured it was worth a shot. It was tough to start and backfired, so I reset the valve lash. First snow storm, it ran great and threw well under load. Second storm, the issue returned - this time, I replaced the plug, cleaned the carb, and once again, gapped the valve lash. Next storm, ran great for about an hour, then started to sputter, backfire and eventually stop running. Any thoughts/suggestions ? It runs the 254cc Husqvarna branded engine.