I just flew a 1400 mile trip and boy are my arms tired...........REALLY! I don 't have altitude hold so I hand flew the whole way at 8-9000'. After carefully trimming for level flight, I couldn't let the yoke go for more than a minute or two without having to grab it to stop the divergence of one to two hundred feet per minute both climbing and descending. My passenger and I sat very still to see if the pitch sensitivity was from leaning forward. It wasn't. The airplane is now open for the annual and I can not find any loose connections in the elevator system, trim system or empenage. I would expect some thermal activity in places but some of the flight was over the Atlantic ocean. Made no difference.
Has anyone experienced this and found a problem or do I need to look harder?
It's a '79 M20J.
Thanks,
Bill