oscope = oscilloscope.
A mandatory tool to own when repairing EFI cars. It shows you data that your average scan tool cannot even dream of, like a bad tone wheel on a position sensor pickup or wrong timing or inverted sensor etc.
whats the difficulty in tear down? - it will take no more than 1 or 2 hour work to tear down the timing casing - if you are crafty you can find TDC of the crank and then look at the camshaft adjusters and also the cams themselves just by removing the valve cover/tappet cover. The lobes point kind of towards each other but upwards - if you are off a tooth that mirror image would be wrong.
A bad chain when reinstalled can cause a jump half a link as you will assume the chain is sitting wrong, while infact the chain is worn out and as its a silent style chain its links seem to miss a tooth, while they dont, the space between the links is also the same shape as the space in a link.
Was the chain tensioner checked by removing the ratcheting pawl? it wears out and the teeth tend to slip.
As I said, Ive done this on evo X quite a few times - the chain itself has been updated with a heavy duty item by mitsubishi and the tensioner has been redone with better hardening on the ratcheting pawl teeth.
Im assuming you are a mechanic yourself, if you are not and relying on mechanics to do this for you, then it will become difficult as my assumption of 1 to 2 hours relies on the fact that you have correct tooling.