1999 Yukon won't start

I have yet another question for anyone that can help me. My Yukon won't start. This has been going on for a few weeks. Heres how it goes. Yukon won't start, turns over just fine and battery has been checked so no problems there. Then the next day it will start just fine. Try again after work, won't start we figued out if we use jumpers cables it will start fine. We do that get the it home few hours later won't start next jump with cable starts right up. Next morning starts up find later in the afternoon won't start again. Try cables starts, starts afew more times after that then back to not starting again without cables. Mind you all this time it is turning over fine battery not low or anything. So some tests ran it was determined the coil and ignition module need to be changed. It then started just fine. Went out again this moring and it is doing the same thing again. Anyone has any ideas. The fuel pump pressure tested fine gas is getting to injectors. What else can it be?!?!?!?!?
Thanks in advance.

When it doesn't start do you have strong spark at the plugs, 65 psi FP, will it start spraying carb cleaner into the intake, these are all basic diagnostic steps for this condition.