Chainsaw Repair

Having some odd and inconsistent runability problems with my 362.  It idles just dandy.  Wondering:
-- Should I rebuild the carb or replace the plug?!`

When I start it, it takes a few minutes to warm up enough before I feel it is consistent enough(not cutting out, able to make higher revs) to start cutting a tree.  Often it will run fine for a while but more often than not it seems just not able to hit full revs, bogs down while just making a standard cut in a 12" tree, and occasionally runs up to higher revs on a road of up and down cycling that makes you feel like there is something stuck in the high speed carb jet feed-- like a spec of dirt is plugging and unplugging it??

An odd thing happened a week ago:   I started cutting the front wedge, horizontal felling cut, and it totalling bogged down but would cut, more or less normally, in a standard vertical cut on a log.  Still would not hit full revs.

Today:
-- pulled off air filters and air hosed them down -- pretty dirty, but restarted the engine with no filters and it bogged down the same. . . continued. . .
-- pulled the plug:  pretty wet, even the ceramic and tip(see image)
-- re-installed tight and the engine ran up to quite high Revs, it seemed as if I had fixed the problem by pulling the plug and re-installing??!  NO, CAN'T BE.  So,
-- pulled the plug again and although the threads were wet the tip and ceramic were nice and dry, brown to tan color(images)

Later on today: started it cold and this time revved it high, but on the way up, lots of quick hesitation-- still, idles great.

My guesses:   
-- carb rebuild to clear out passages in high speed circuit(bogging and hesitation).
-- engine getting old, maybe not so great compression, check that.  How much is reasonable for a 10 year old?
-- new plug?  (hesitation), it is not that old 3 years or so?

YOUR guesses here==>

Get it started on idle as best you can. Then remove the starter recoil to expose the flywheel (be careful- the flywheel will be rotating) Grap a can of carb spray or similar and hold up a bit of cardboard or similar against the air filter housing to prevent any spray from the can going near the air filter. Then while the engine is still running, spray some of the carb spray around the flywheel area- if you have an air leak through the crank seals, then the revs should increase almost immediately and then die back down. Do it two or three times to be sure. Like i say- make sure you don't get any near the carb/filter area as that will give you a flase reading. Another tell tale sign even before you do the spray trick will be a lot of oily residue inside the recoil housing around the flywheel area- this being caused by the fuel/oil vapour escaping from the crank seal. Hope that helps, as doing a complete leak down test is quite labour intensive and you will need special tools to conduct it- this method at least confirms the problem.