Small Engines (Lawn Mowers, etc.): Poulan string trimmer engine problem, exhaust ports, string trimmer

Question
I have a Poulan PL25 string trimmer. It was working great and I cut a little longer than I normally do.  The next day I tried to use it. It would run a little, start to sputter and die out.
I took out the plug and replaced it.  No better.  Disassembled the carb,cleaned it out and cleaned the fuel filter. Still starts, runs 10 seconds, and dies.  Any suggestions?

Answer
First, try loosening the fuel cap to vent the tank.  If this corrects the issue, the tank vent is at fault and will need to be cleaned or replaced.  The other area of concern may be plugged exhaust ports and/or muffler/spark arrestor.  Hope this helps.