Valve adjustment is hydraulic, they are prone for sticking valves. Have you done a compression test? I had one it used to run fine but once hot it dropped onto 3 cylinders. Once it did this if you stopped the engine and restarted it you could here it was down a cylinder when cranking. It was a sticking valve.
This is ONLY to be used to report flooding, spam, advertising and problematic (harassing, abusive or crude) posts.