I did have this problem and solved it as follows:

When rocking stars. DIsconnect  the A/P and  look at your yoke in VC mode. It should be making rapid turns left/right. Hold the yoke , very slowly correct the turning until rocking completely disappeared.

If you having pitch up/down again disconnect A/P and slowly push/pull yoke until elevator stop vibrating. You can also check elevator at outside view to see how rapidly elevators vibrating. When elevetors stoped . Then you can connect the A/P.

This is not the way correct the problem permanently, but better then nothing.
Good Luck ;)