I have a B&S 14.5 HP Mod# 280H07, Type 0036E1, Code 060103ZD, Ser# 06012ZD62884 (from housing). This engine replaced one on a swisher trail mower, it was installed in the spring of 2006 (by a shop). Worked fine for a year and a half. Used it early this spring until a wheel fell off, had it rewelded back in place. Then it would die shortly afterwards, this this for a number of times then it finally remained running for at least 45 minutes then stalled again. I dropped the fuel bowl and cleaned it out and replaced the gasket, replaced the fuel filter and the air filter. At times it will stay running and run for over 45 minutes to an hour and a half but then it will start dieing again. This engine has less than 50 hours on it since installed, if it had dirty gas or water in the line it should have gone through by now (i am guessing). What can I check??

Did You Check/clean Spark Plug?

Check for spark, immediately after it stalls. Could be an ignition module failing.