Oh the bearing is the cam sensor?

 

A couple of things come to mind. But because changing out the valve gaskets seemed to alleviate the problem for awhile I would look at the valve seat. Have you tried a compression test on that cylinder ? A weak valve spring may also be suspect. So you may want to try a vacuum test. If these pan out, then I would look at a chipped or cracked gear tooth, for the cam, or crank sensor. Which ever the vehicle may have. A craked tooth, or sludge build up on a tooth may be hindering the sensors preformance. Causing the plug to fire late or early.

 

I know you have had a lot of good suggestions, and tried a bunch of parts and tests, any updates?

I had the exact same problem, and after countless hours and parts, I ran a compression test and found that I had WAY low compression on #5. After some digging, it was a bent exhaust valve. My heads were so cracked they couldnt repair them with a regular valve job, so a new set of heads fixed the problem.

Short of all the electrical tricks you are trying, might just have to get down and dirty with some mechanical duties and start diggin for gold!