I have a 4 cycle troy bilt snow blower that is hard to start. I ran the fual to empty last year and then refilled this year. The engine start on high choke but will not continue to run when taken off of high choke. It will only run for a short perod of time even on high choke. I;m sure the answer is gas filter related or I hope a new spark plug will fix the problem. On a scale of 1-10 on small engine repair I;m about a 3 or 4. Thank you for your help