Cylinder 1 Misfire Under Load

[Number4]

my '05 4.0 is misfiring on cyl 1 when under a load (or +2k RPMS.)
No misfire at idle or even when RPMs level out.

Coil, plugs, wires are all relatively new.
Using Forscan and show no injector issues.

Plan to test resistance of wire one and pull plug for visual inspection.

I'm not understanding why the cyl would only misfire under a load but not at idle.

 

[Number4]

Issue ended up being the plug wires. Went to pull wire one off and the metal portion stayed on the plug.

Wires and plugs had approximately 15k on them.

 

[Drewmcg]

What brand wires?

 

[Number4]

NAPA's Belden Edge wires.

 

[Drewmcg]

Thanks. Scratch those, then! When I replaced mine with Motorcraft oem wires recently, I was surprised to find that the new wires had more resistance than the ones with over 100k miles on them (but I used the new ones, anyways).

 

[TechGuru]

For long term parts I would only use Motorcraft.

Wires http://www.rockauto.com/en/moreinfo.php?pk=951589

Plugs http://www.rockauto.com/en/moreinfo.php?pk=949946