Sethhatfield - I have had something similar with my 4.8is, though I never had to try 5 times , more like 3-4 times max and then the engine fired.

a. Couple of years back on my trip to Maine i suspect bad fuel quality caused this issue , did not repeat for 8 months ..once i came back to CT.
b. After 8 months from the first instance it started happenning again, and my battery died too, I ended up changing the battery to AGM type and have never had any issue since.

I did not try to diagnose this issue so just off my personal experience, hope this helps.