My '94 K2500 342K miles, usually fires right up. Batteries are due but I've kept them on a maintainer. Fuel filter likely due for replacement. Check Engine light flashed randomly a few times last week. Today typical start up:Glow plug light came and went, fuel pump working; ran rough for about 10 seconds and stalled. Will not run. I've never replaced IP. So, what are IP failure symptoms? Other possibilities? Thanks in Advance!