Stalling and non starting quick check
 

I recently had my 2003 gmc deisel stall out on the road, tried but could't get it started.
Paid one of those mechanic on the internet, simple check. Pump the filter housing pump and see if you have a fuel leak, there suction run if you see fuel its most likely a air leak. Found a company that rebuilds the fuel filter houseing for 275.00, the way it sould have been done the first time. Check out bmaxwrench, they shipped out the part overnight.