Allright guys, need some help. Got cold at work today, whent to drive home and it didn't seam to run quite right. Should I have let it warm up more? 4 miles down the road it hesitated a little and began to backfire flames. Started it back up and it did the same. I know the thing is running rich, could smell it. Guy I bought it from says he always ran it rich and that u had to let it warm up good. Is this right? I'm lost, this is brand new to me. Help?