Alright.... My truck has been starting hard for the last year or so (excluding a couple HOT summer months) I know the glow plugs work. I just replaced the glow plug relay. Just replaced a valve cover gasket and UVCH. AND I just put all new o-rings on my injectors. The o-rings that I replaced were original and they looked fine (at least they weren't cracked or falling apart). In about 2500 miles I haven't lost any oil at all. Im not loosing coolant, and the coolant doesn't look dirty. Is the next step injectors? They are original and now the truck has 194000mi on it. The hard starting consists of taking at least 10 secs. to finally start coupled with heavy white smoke fading into black smoke then once its running there will be a white haze out of the tailpipe until it warms up. When it is really hard to start ill also get black puffs of smoke when i rev the engine (again only until it warms up)...
P.S. What should the voltage drop at the GP relay be when the GP's are under a load