Small Engines (Lawn Mowers, etc.): Push mower will not stay running, wargo, lawn mower

Question
I have a MTD pushmower with a B&S 5.5hp commercial grade engine that is about 7 years old.  The engine was replaced under warranty about five years ago.  We moved two years ago into an apartment, so it was not used for a year and then last summer, this problem began.  I don't use it very often, but need it for a few areas of my yard.  I recently changed the oil, air filter and the spark plug and put fresh gas in it, in an attempt to fix the problem, but this did not work.  I am able to start my lawn mower after pushing the primer button a few times, but it does not stay running.  It will run roughly (chugs in a out) for approximately five seconds and then die.  Yesterday I took off a protective cover and could manipulate the throttle by hand and could keep it running (roughly), but it was sluggish and not reliable (I constantly had to manipulate the throttle to keep it running).  I don't know what would create this problem, please let me know if you have any suggestions.

Thanks,
Dave Wargo

Answer
Hi Dave,

The carb most likely has dirt, debris or gummed fuel inside.
You will need to remove the carb, disassemble it, clean all the small internal openings and blow it out with compressed air.   Probe each and every hole with a small wire.   A carb rebuild kit wouldn't hurt either.  

Let me know how you make out.
Michael