I have a very stubborn 6.2 CUCV I'm working on and need some help. Already replaced the INJECTOR PUMP and NO DIFFERENCE. So here's what it does.... It has a strange condition I haven't seen much on these 6.2 CUCV's over the past few years of working with these. It truly has me stumped. Glow Plugs are good, fuel clean, lift pump working fine, no visible fuel leaks, new fuel filter, IP gets power, and it runs good once it gets going. But what it does is when cold it will start up, run up for a few seconds the FIRST TIME, then die. Then from that point, if I re-cycle the glow plugs and try to start it again, it just crank and cranks. But after maybe 2-3 long cranking sessions and some application of throttle it will hesitantly start up after some stumbling and coaxing. It will then more or less smooth out and run fine and idle nicely after maybe 30 secs. Now, when I turn it off and then fire it right back up, it starts. BUT, if I let it sit for 30 minutes or so, NO luck. It won't start at all, not even with coaxing. WHAT is going on with this truck? Its a clean truck, rust free, and the rubber return lines look decent, not leaking or too dry.