Small Engines (Lawn Mowers, etc.): mower runs then quits, murray mower, intake tube

Question
Have a 3.5 classic; motor slows down, sputters, then dies; will run again for a time after priming. Cleaned carb (no new parts, sealed diaphram to gasket to prevent leaks),and it ran fine for 15 minutes when put back together.  Next day it started fine, ran for 5 minutes, then died. Repeated cleaning etc. process three times with the same results. I'm wondering if it's electrical but then how come it always starts up again after priming.  

Answer
Is it a Murray mower?  Did you relpace the diaphragm and gasket?  Did you blow the carburetor out with compressed air?  How old is the engine? Was there a screen on the main fuel tube of the carburetor?  If so, try removing the screen and see if the mower will run.

Finally, check the intake tube screws/gasket where the intake tube is connected to the engine block.

Let me know what you find.
Eric