wet plugs on the threads is usually caused by the donut seals in the valve cover.

 

That's logical. I replaced the valve cover gasket not too long ago.

My friend's 2ZZ, with 150K original gasket, also has wet thread on plug 4.

 

You may have a sludge issues, I'd suggest pulling the VVT screen and checking it for blockage, if it's partially blocked then you may need to pull the pan and inspect the oil pick up screen for sludge as well as check under the valve cover. Why did you run a 20K oil change and run it for 100 miles with low oil?

 

I had a very busy time and just did not take care of the car. The oil was thick and black when dumped.

What is the VVT screen? Where is it?

Why does the engine shakes and ratlles so much in idle?

How could the sludge cause it?

Compression check 193 200 210 230. What would cause cyl 4 to have much higher compression than the others?

 

I suggest that you obtain a mechanic's stethoscope from Autozone and use it to listen to different parts of the engine to diagnose the rattle source.
It could be from the valve train or from the bottom end or from an engine accessory. It could also be detonation inside a cylinder, if something in the timing or ignition has gone bad.
Nothing more than speculation can come from an on-line diagnosis.
Hope this helps.

 

I did try to locate the source of the noise. Seems to come from the timing chain end of the engine.

Will borrow the stethoscope.

Thanks for your tip.

The engine leaks oil from the main seal, about 1 quart every 500 miles or so. I was lazy so kept adding but not changing oil and filter. Bad mistake.

 

I read the thread on cleaning OCV strainers, both Cam gear and Lift. Lack of oil probably cause wear on the cam gear and timing chain, therefore the noise and vibration during startup. After running the engine a while, it sounds smoother, probably as more oil is force through the strainer.

One guy mentioned Marvel Mistery oil will also clean these 2 strainers. It's supposed to dissolve sludge.

Looks like the lack of oil to the cam gear during start up cause noise and vibration. If Marvel Mystery oil can clean the sludge off the strainer, it may help some. Will try that. If not, will take the strainer out for a clean.