My 94 GS-R was idling rough and seemed down on power. I just purchased this car a day ago. Owned by older people (55+ AARP and such) its entire life. Never modified. Today I am trying to track down the idle issue (which we determined was cyl 2) and I decide to do a compression test on it. Numbers come back
Cly 1:210
Cly 2:35
Cly 3:210
Cly 4:210

After putting a half cap of ATF in cly 2 the compression came back at 60.

There is no smoke coming out of the car, at any RPM, valve train seems quiet and in working condition.
The Oil is completely clean and still fresh, along with the coolant.

I know the possibilities are (in my head)
-Blown Headgasket (not likey as clean as the oil and coolant are)
-Burnt Valve?
-Blown Ring?
-Bent Valve?

Has anyone had any problems like this? It has a 155,xxx miles on it and is in really good condition the only thing is while the older man was driving it (putting around town) he used 87-89 octane in it. But I would think if the car was detonating the other cyl would not be perfect 0% difference across the board. (minus 2 of course). I am well knowledged in automotive engines but I am looking for some people who have had personal experience in something similar happening and what was the culprit. I'm angry since this car was mint but if the engine is no good then... Thanks for the help.