1999 Suburban 2500 454 misfire

[gearheads78]

OK my new to me daily driver / tow rig is killing me. A couple days after I started driving it I randomly started getting a misfire. Over a few weeks it started getting worse and I watched it while driving on a scanner and its coming from #4. To get a base line I did a tune up with plugs, wires, cap , rotor and new 02 sensors. Fixed!! Drove like a dream for 3-4 days then started to get a occasional miss again Over the coarse of about 3 weeks its gone from occasional to 15000 misfires on a 20 miles commute home. It's still #4.

Start looking deeper. Misted water on the wires in the dark no arcing. Pulled #4 plug looks great but replaced anyway with no change. Replace wire with another new wire.. no change. Compression test on 2, 4, 6, both hot and cold all 135-138 psi. Injector balance test... all 8 with in 2psi.

It makes no sense to me! What the h##l am I missing? Anyone have any idea? I have an injector on order and hope to have it in over the weekend but if that does not fix it my next step might be a match and a can of gasoline.