WW
Only seen/flown one example of the 365N Sperry. It's data transducers are slighlty different from other 7000 installations, for example the S76B. The ALT PRE and baro info is supplied from the altimeter and not a separate ADC unit. The altimeter has an encoding function which supplies the AP computer with the signals to drive the altitiude functions. Dropping the ALT could be many things including the engaging of another pitch function, or the disconnection of the CPL'r, to an AP computer malfunction.
Shawn is quite correct, more observations are required to make a guess as to the cause of the de-coupling.
As for the yaw, there are rate gyros and other associated yaw components mounted under the floor that can cause weird yaw effects. Best trick, find a good E&I greenie who knows the type of AP.
If it's the one in QLD then that's the one I've flown when it first arrived in country for HR. Their greenie is good on the unit so might pay to give him a ring.
Geoff