But it doesn't make sense that only #4 does it and not 5&6. We also went throught ignition trying to move it and couldn't

Are these heads prone to cracking? Perhaps there’s a hairline crack in the #4 chamber. 

I'd like to see the results from another compression test. I'm beginning to think it may be a bad oil ring as suggested by Zed Head.

But oil ring shouldn't affect compression numbers

I haven't read the whole story but do a comp.test .. first cold then one hot and note all findings here.. that would be the day that we don't get an answer!!  Together we'll get it out of that engine what is wrong!!!  8 years is rediculous..

Also while doing the compression test, I’d like to see the valve cover off and some shots of the valve train. Perhaps there is something out of wack

Compression test first of course. Leak down test after that if the first test isn’t conclusive. My 2 cents..

If that plug is indeed carbon fouled instead of oil fouled then we need to see the cap and wires.

Close up of inside of cap as well as exterior of cap.

An Ohm meter reading of all wires from cap inside terminal to end of plug wire.

Post reading for all 6.

7 minutes ago, gundee said:

If that plug is indeed carbon fouled instead of oil fouled then we need to see the cap and wires.

Close up of inside of cap as well as exterior of cap.

An Ohm meter reading of all wires from cap inside terminal to end of plug wire.

Post reading for all 6.

Here is a closer pic of spark plug 4 and one of all the plugs 1 2 3 4 5 6

No oil at all. Carbon fouled due to long idle during traffic jams

22 hours ago, Yarb said:

Compression test first of course. Leak down test after that if the first test isn’t conclusive. My 2 cents..

Compression test results

are those numbers dry or wet? hot or cold? throttle fully open? Seems low, but at least consistent