If I don't have it revved up & get into any heavy grass it dies. 4-stoke I've cleaned the foam filter & shook out the paper filter which was new a couple of years ago (I've tested with the filter off & don't notice any difference).... The only way I can get it to stay running it will keeps getting faster if no load but with a little extra load it bogs way down. Adjusted the screws every which way, the only thing I have not tinkered with is the float height & I don't know how to go about that or if it's even relevant. Being 17 years old it probably needs a carb rebuild. Not hard to start but the throttle has to be pushed full on to starting to engaging the choke to stay running. I've tried adjusting the cable where the choke goes off sooner. Does not smoke or use oil, has been a great piece that I wish I could get a new one just like it...but I understand they no longer make them ...