FUEL
Change out the air filter, take it out and run it really good till it is really upp to real temperature...then come home wait for it to cool off some an dcheck it out. Fuel is wierd in that cold weather causes you to use the choke and then again the engine may not see long enough temperatures at the proper temps to get it all out of the system...beware of using the choke any longer than necessary...not a good thing...it's really rough on plugs...The reason for the airfilter is because if it is even slightly full it will cause the motor to run rich and cause the fuel to stack...and you will only make matters worse. The airfilter assorbes mositure like any paper does and becomes less effective at passing air when it is wet...and even after it has dried out...Too drain out all of the old gas and put FRESH gas in it before you run it with the new filter in it. Old gas does break down...even with STA-BIL in it. Save the stuff to put in with the lawn mower gas can...make sure that your idel is set properly and use the throttle instead of the choke once it is started...