My Poulan runs for about 5 minutes then dies and won't start again for about 20 minutes. Then the same thing. Any advice?

Hi,
Sometimes water (condensation) can get in the gas. If your model has a bowl on the bottom of the carburator, loosen the bolt and ease the bowl down and take it off. You will spill gas out of the bowl but that's ok. look at the spilled gas while you're at it and see if you see beads of water... tell-tale sign of this as being the problem. I'd get a paper towel and dry the bowl out before reassembling. To make sure there's no water in the gas tank, you could loosen the fuel line, drain the gas into a container (preferably glass so you can see if there's water in the bottom of the container, afterwards). If there was water, you might swab the bottom inside of the tank out with a paper towel. Reassemble everything and put in some fresh gas. You might can re-use the old gas, just don't pour the water back in... ha.
I hope this helps... Good luck!