2002 Nissan Xterra Replaced fuel filter, now won't start

The truck was running a little rough, and I know that there was a possibility of contaminants in the gas tank, so as the least cost alternative - I changed the oil & filter, air filter, added some EFI cleaner to the tank and most importantly changed the fuel filter per instructions on the Xterra forums. This looked like it hadn't been changed in a while. I pulled the fuel pump fuze before I did it, and replaced it after I was done.

The truck started right up and ran GREAT (as it had 50K miles ago), so I thought that I was on the money. I drove it 15 miles to someones house, 15 miles home - and then when I tried to start it, it just turns and turns and won't fire. It "coughs" once and then just keeps trying to crank.

Going back to my basics, I verified the fuel fittings where I had worked weren't leaking, and that there was gas in the tank. I verified that the fuel pump fuze was good. Then I verified that that there was spark (pull plug, 3/16" away from block, watch blue spark) - and I don't think it's air. So, what is my next step to verify that the fuel pump is working and putting the correct pressure in there? Any suggestions as to my issue?

Steve
Charleston, SC