If it'll cold start by pulling or push starting it, you're most likely looking at weak batteries/starter. Everyone around here says these trucks have to really spin fast to start, like fast enough that you cannot count the revolutions when you're cranking it. If you have a tach, I'm pretty sure I read here somewhere that it needs 200-300 rpm cranking speed. You need two 1000 amp batteries in good condition, good connections on the cables everywhere, and a strong starter. Look at the positive battery cable where it connects to the passenger side battery for corrosion up inside the cable insulation. I'm sure some others will jump in here soon, they LOOOOOOOOVE fixing hard start issues.