The C208 seems to be having some severe Dutch Roll since the patch that caused Career Mode to crash for players or the server-side fix to repair that CTD issue.
Flying with Yaw Damper [Y/D] on seems to help, hopefully it gets fixed soon.
EDIT: Here is a Bug Report about the issue.
Cessna 208 Caravan wobbling on autopilot - Bug Reporting Hub / Aircraft & Systems - Microsoft Flight Simulator Forums