For the hell of it I would disconnect the knock sensor to see if the ecm is pulling timing. if that doesnt work time to do a compression/ leak down test . then you will know if its the valvetrain.

 

If I had to put everything on a single guess, it would be a burnt exhaust valve or cracked exhaust port.
- but if you KNEW your car, you will hear it at the exhaust tip.
A compression test will tell you quick.
If compression is good, check rocker travel, for both valves.
If it's rings, taking off the oil filler and listening will tell you quick.

It's not unusual for a chronic miss to go away temporarily when you change injector or plugs.
If your compression is a little low and if you arent using oil and dont hear the 'putt' of a burnt valve in the exhaust and it looks like valve travel is good.. just buy 1 or 2 stage hotter plug for that cylinder and see what happens. The misfire will probably go away.

This assumes you dont have spark jump on #6 wire. Did you check in the dark?

 

Compression was tested when it was brought to the dealer, cylinder 6 was low. Everything plug wise and sensor wise has been checked or changed. Im leaning towards valve issues whether a broken or worn spring or burnt valve. I dont k ow where else to look really

 

Well just thought I would post an update. I was on my way to buffalo wild wings tonight to buy food cause im getting fat and never cook for myself anymore... BUT.. when i was leaving i started my truck and the misfire was gone again!! the only thing i can think is that it is a valve with some carbon build up. I have been using mmo in my oil and also the fuel tank so maybe that is freeing up some of the carbon? thats the only thing i can think of. Any ideas?