won't start

[Copyman]

I have a 2000 e-250 with a 5.4 in it. Van started up last night to move it out of the way then a hour later it wouldn't start. replaced the fuel filter as it was time checked the valve and have fuel pressure and it turns over fine just won't start. Changed out the crank position sensor , still wont start. Has Cop's, don't Know how to tell if they have spark. Engine had been idleing rough but ran good as soon as you give it a little gas.Has about 400k on the engine that is in it now. Any one got any ideals other than trading it off, Still got another 400k to get out of it. Changed out the cam position sensor still didn't help, plugged a spare coil up to one of the clyinder and checked spark. It has spark and has fuel pressure on the rail but doesn't crank up HELP HELP