awesome, glad it worked out to a simple fix!
these things can be a bear to bleed, i've had a few throw curve balls at me and while it can't be logically speaking it seems random. one will bleed easily, without hardly doing anything more than filling, another will be a pain.
I thought a blown head gasket problem did not produce an intermittent overheating problem, just a constant overheating problem
not the case. there are multiple failures modes and these engines tend to have very specific failure modes.
EJ25D's randomly overheat every time.
Later EJ25's (like 2000+ OBW's) do not overheat because of the headgasket leak. (though they will eventually overheat if you let the coolant get low, but top it off and it won't overheat even with a failing headgasket).
(because he said compression ratios were normal in left side) the head gasket had not failed.
compression tests are almost useless on an EJ25D. EJ25D's often pass a compression test when headgasket issues first appear because of the way they fail.
both headgaskets should be replaced. the problem is so prevalent there are websites devoted to the issue, this website even has a "headgasket" dedicated forum and headgasket log thread, and it's not much extra work to just replace the gasket while you're in there. while it's the next phase EJ25, Subaru came out with multiple headgasket revisions up until 2010 even, a coolant conditioner (stop leak), and had a 100,000 mile extended headgasket warranty on 2000-2002 EJ25's...they are prone to failure, i would take the opportunity to do both.
the aftermarket ones will not work
aftermarket tstats work, it's not that 100% of them fail, OEM is just higher quality and has lower failure rates.