So the other day i was driving on the highway doing 80, no real load just cruising. When i went to give it some more the car hesitated then through a flashing CEL. Car began to have very rough idle, but was very smooth under a load. No smoke, no lack or performance, nothing is being consumed. I pulled the codes and i have 3 for miss fires. Cyl 2-4. I changed the plugs with NGK plugs, left me with Cyl 2 miss fire. I undid the wire to the coil thinking it had a bad coil. Once unplugged there was no difference in the idle. Following morning i replaced Cyl 2 coil. That did nothing. When engine is under a load, the light stays steady, once off the load goes back to flashing. i read about ring land and starting looking into that, did a compression test, Cyl 1 3 4 was around 100 and Cyl 2 was 25. I checked for blow back and there isnt any of that either. I just changed the oil and there wasnt a trace of coolant or gas or metal shaving in it I always use mobile 1 syn 5w-30. I'm starting to think its a stuck valve. Please help out with any ideas.
02 WRX 165XXX 35k on rebuild
STI IHI turbo
3in Catless TBE
XPT open source tune
Forge Blow Off Valve
93 octane every tank but 2 tanks
oil changed every 3k
What ive tried-
Seafoam- vacuum line/crank case/ intake
What i was thinking on trying
Pressure Cyl 2 to see if it holds
Bars Head gasket fix
And if that all failed, finding a cliff. Please help me out running out of ideas.