Can't solve misfire

02 v6 4x4 auto.
Check engine light came on for cylinder 5 misfire.
Since it is getting in the way high miles now, decided to do a tune up anyway.
Replaced cylinder 5 coil, Spark plugs, wires, cylinder 5 fuel injector, fuel filter.
After all that I still get cyl 5 misfire. Changed coil to cylinder 2, fuel injector to cylinder 1. Still get cyl 5 misfire.
Am I looking at needing to do a leak down test for burnt valves? Truck doesn't smoke or anything so I assume compression is ok.
Anything else I am missing?
If it was wiring going to cyl 5 coil I would think I'd get a code for cyl 2 misfire as well since they both run off the same coil.

 

On the old 3.0 V6 that corner used to get really hot and burn valves, the 3.4 is a little better, but there are cases of headgasket failures and valves burning.

A compression test and a leak down test would definitely be the next step.

 

I have had this very same problem. I did a tune up and it turned out that the spark plug had a hair crack in the ceramic shoulder. It was arcing out the side on the block rather than down at the electrode like it's supposed to. I didn't notice it when I installed it, but when I pulled it out there was obvious discoloring from the ceramic getting hot. I went and bought a new plug and good as new. Check it for a crack, and if you can't find one just go get a new one and try that. Who knows how those parts are treated before consumers get them.