Like Squeeze said, check for vacuum leaks.When it back-fired, it may have blown off a vacuum line or even(rare chance) that it could have blown out the carb base-plate gasket.
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The fuel flow could still possibly be restricted wil crud.Does the system have an in-line filter?

There is enough good in the worst of us and enough bad in the best of us that it does not behoove any of us to criticize the rest of us.
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Be yourself. If you are ever lost, It will be much easier to find yourself if you know who you are!