PA34 Seneca V autopilot lateral modes sometimes do not follow instruction

The autopilot on my PA34 Seneca V is glitchy. Sometimes after takeoff I engage the HDG button and the aircraft turns to about 160 degrees to the left of where the bug is. I can still control the heading but it is coming nowhere near the bug, as I mentioned almost 180 degrees off. Also when I engage the GPS mode direct to somewhere it seems to take me direct to the VOR nearest the airport I just departed, not the programmed VOR. Both of these issues with the HDG and NAV happen always at the same time and the autopilot vertical guidance is always ok. The only way to fix this seems to be to reload the aircraft, and after obtaining clearance online and loading the fuel etc it is a pain to restart the flight. Any ideas??