I run a 3" straight pipe and it sounds great. Believe me I am not into loud vehicles. The turbo breaks up the exhaust pulses so no muffler is needed. I run a pair of Dynomax (Walker) Super Turbo Hemi mufflers on my 400ci 79 Bronco because I like quiet.
Ohm out the glow plugs. Disconnect the connectors one by one and check the glow plug. They should be less than one ohm resistance to ground. If you drove it to where it is now it will run with the pump that's on it. The next thing to check is for air in the fuel system. Very typical problem...
I thought it was a big block Chevy plate... like a 454..
Anyways, if the fuel leaks back when setting it's usually the injector return lines and most likely the o-rings under the caps. It can also be related to the fuel filter and header.