Ummmm, this is really confusing. You stated that the problem occurs when enabling the avionics too soon AFTER enabling external power, but your first list has "turn avionics on" BEFORE enabling external power !?!?!?!?!?
Your second list has the avionics being turned on AFTER enabling external power, but that is the list that you claim is working fine!!!!
In any event, I tried this both ways and my power levers NEVER moved at all.
This problem sounds like an issue with your hardware or an associated plugin.