The 2 per pedal revolution implies something to do with pedals or bottom bracket. Check for loose pedals or bottom bracket cups. Check for Crank arm tightness. If you have an external bearing crankset, check the attachment of the left crankarm.

You know, it's against natures laws to have everything on a bike work just right. If you persist on fixing too much, something else will just break or go out of adjustment early.