1997 Econoline 4.6L miss

Son-in-law says he was driving the 1997 Club Wagon, seemed little sluggish then recorded a code; a scan indicated a Miss on #8. Not a blinking CEL, solid. I've told him to clear the code and drive it to see what happens.

Truck only has 135,000 on it and I had the original plugs with new OE platinum's in the last 2,500 miles.

I'll assume the #8 plug is OK, plug wires are the originals as are the 2 coil packs, so one of these could be questionable. #8's injector?

Any common failure for this series or engine that would cause this?