Yesterday the blower was running great. Today I noticed it idled fine, but at full power it was bogging to the point of almost stalling. I let off on the gas to keep it from stalling. I can get it to full power, but only briefly before bogging. Happened in the course of one day...I have a new air filter in it, original plug. Unit is 2-1/2 years old. Any one else out there experience a problem like this??