CO=PILOT not behaving correctly

Dear Devs. I am very impressed with the improvement you have made to the Caribbean island of St Maarten. Superb, especially the water. BUT, my route, controlled by co-pilot from Grande Case TFFG runway 30 to St Maarten TNCM runway 10 is a disaster. Basically small plane takes off then takes a course to the left, then turns to the left again to land. The take off and landing is fine but the middle section is a total joke. The plane continually rocks violently from side to side trying to get the plane to a level position, once it gets to the turning point in line to land, miraculously the plane is stable again. This is not the first time it does this behaviour, its been doing it for at least a year. The co-pilot used to be so smooth and stable but not for the last year. I have always used co-pilot for the whole flight whichever route I flew and it was fantastic, but now its gone to pot. PLEASE PLEASE FIX IT. You can do it because you have done it before. I know you have been creating new airports and such but the co-pilot problem needs fixing.

Hi Jan. I used the KING AIR plane. Flying at 1000ft. Third leg it goes haywire and starts rocking.

If I just fly with the 4 arrows on screen and then press land at nearest airport, the plane flies as smoothly as silk because he anticipates the deviations. BUT, if I fly with co-pilot with my own waypoints in a route, that is when the plane is erratic, when it turns at the waypoint it does not anticipate the turn and thus turns too fast and overshoots. co-pilot used to anticipate the deviations all the time, but not for about the last 12 months.

P.S. Just completed my most complex route I have ever done in Switzerland and I used same KING AIR plane at 4000ft. Every part of the route , every twist and turn between mountains was perfect. So why not on the ST MAARTEN route?