2008 streetmate starts easy, accelerates to 15mph then sluggish and misfires.

Hello,,, check your air cleaner,,,,,clean,,or replace,,,,check plug,,,,check plug gap,,,,,check the adjustment on your carb. ,,,VERY IMPORTANT HERE,,,,, check your exhaust pipe,,,,,it may be getting clogged up with oil,,,,, clean it out,,,real good,,,,,, if that gets clogged up,,,you will all kind of problems,,,,,, check one thing at a time,,, and test,,, i would start with your exhaust pipe,,,,,remove,,and inspect for a build-up of oil,,,,, being 2 -cycle,,,,this has to be cleaned every so often,,,,pretty easy to do,,,,,any more help,,,feel free to contact me,, JOEL