hard start,long crank

[loweredpowerstroke]

i am new to the diesel world, just picked up a 99 2wd x cab long box, with 229000 miles on it with a auto. The only thing I been having is that it does not like start right up after it sits over night, it cranks and acts like it wants to start but doesn't start or it will start and die right away unless step on the gas pedal a little bit. the smoke that comes out is a off white greyish color. as for mods the is none that i know of besides having blue air filter. batteries are new last feb, new alt and waterpump a couple months ago, haven't tried plugging it in have to wire up a outlet near where the truck sets. the guy i got it from didn't have any probs starting for him but he always had it plugged in. Any help would be great. all the diesel guys around me are cummins and duramax guys.