Chasing the white rabbit...Help

[Nasanieru]

Ok...got another stumper for all you guys. We had bad storms today, really bad ones. Before the storm the truck was running great, after the storm the truck took a dive off the deep end. Finally, after driving it a couple miles it produced a code for me P0305 and only that 1 code. There in lye's my problem.
There is a bad odor which from what I have been reading says, coil pack. Don't think it's the plugs because I just changed them. Have been having starting issues before this started which could be a sign for injector. Not wanting to throw a lot of money at this, and was hoping that we mite be able to figure this out before having to make multiple trips back and forth to the auto store. Not that I hate the auto store...lol.
If anyone has some info on the subject I'm all ears...oh yay, It's a 99 Expy, EB, 5.4L - and cylinder 5 is the trouble child.

Thanks Guys

 

[FordandPolaris]

My guess is you have water down in the plug hole. This causes the coil to short to the block as opposed to jumping the gap on the plug. Pull that coil pack and blow the hole out with a compressor, if the problem persists, replace the pack and plug (since plugs are cheap and it doesn't make sense to do all that work and not change that quick too).

My guess is that the coil has been going bad, and the storm was the last push it needed. The codes usually only come up if the cylinder is completely dead.