my brother has a 01 f150 with a 4.2l v6 and i had to go flate bed it home the other day it was running rough will barely idle and seem to be running on a few cyclnders so i changed the coil pack and plugs not any chang in it any thing else??? also when you rev it up it seem to smooth out a little but you can hear spark nock

 

Definite electrical problem.Did you check/change the plug wires? The crank sensor could be bad.Go to this website and ask your question there.It is run by Ford techs;
www.flatratetech.com

 

i replaced plugs, wire, coil, egr still didnt fix it still to found out the number 6 was not firing still. so come to find out no compression and further went into diagas i finally came across a broken valu spring