So a few days ago my impreza 92kw soch while accelerating started to stutter or hesitate. And there is sometime with that hesitation a knock sound, the sound comes not lika a metal knock sound, more like rubber. And the knock feels through gas pedal. Hesitation only start at hard thorttle. Changed spark plugs because there was oil everywhere so I cleaned everything and installed new spark plugs, everything was fine for one day, and today it starte again to hesitate. any ideas what might be damaged and needs to be replaced?
​​​​​​