Is my 147s dying??

Hello. After I whittled through all threes, now nevertheless my question: Facts: 147er Alpha, Bj 2002, 108Tkm error in the engine monitoring system flashed first, then 5min later continuous light. Up on no power in the lower speed range (3000), restless idle hardly revolutions, next day workshop: spark plugs replaced, cylinders would not get enough compression, it would be glued (oil change too rare), solvent in and 24 pcs. let work, no change. there are 3 possibilities: -Build the engine apart and clean it up,-continue in the hope that the problem will be solved by itself (Sprit consumption??),–he’s stuck and then I need a new engine anyway. Question: isn’t there another fourth possibility?? Can’t it be something else, even if the Mech has the \