! Found the Real Problem ! - Timing

[PHOENIX]

This is a continuation of my timing problems I have been having.
Even with the new #1TDC mark I still have rough idle and valve clacking and pinging at low rpms (3000rpm+).
Driving me nucking futs.
Well I decide to pull all the plugs again and check them because the #4 cylinder before had the damaged and fouled plug. Well I pull all the plugs and #4 is starting to have the same problem again, all others look fine. I have less then 10 miles on these new plugs. See the picture below.
Old (Bad) = The plug from cylinder #4 that I had in for awhile and pulled out when finding the #1TDC
New (Bad) = The plug that's currently in cylinder #4 that has only been in for less then 10 miles and is already showing oil fouling).
New (Good) = The plug that's currently in cylinder #3 that is in good shape. All the old plugs except that in cylinder #4 looked good like this "new (good)" one.

So here is my questions.
(1) Do I have a worn piston ring, bad valves, or bad valve seals?
My guess is bad valve seals or valves.
The truck has been run low on oil (1 to 1-1/2 qrts) a few times in the last few months due to me being a slacker. Ill check it every other weekend or so and its anywhere from 1/2 qrt to 1-1/2 qrts low. To make a long story short my old valve covers had a baffle that restricted oil input, so adding oil was a b*tch and I slacked on change the covers (because the baffler and possibly bent covers).

(2) Where do I go from here and how can I figure out which (rings or valves) it is?
I'm guessing its time to pull the heads and take them to a machine shop?
Please help me out.
Thanks, Eddie