I am a dual Canadian/US citizen currently residing in Canada. Can I vote in both the Canadian and American federal elections? Can I vote in the primaries for my party? Am I allowed to cast votes for congressional candidates in the US from the district that I lived in most recently?
For the US, the Uniformed and Overseas Citizens Absentee Voting Act provides that just about any US citizen living abroad who has previously resided within the US is entitled to vote in federal elections as though they still lived at their last US address, provided they'd be eligible to vote if they still lived at that address. If you're overseas on duty in a uniformed service of the United States or as a spouse or dependent of such a person, it's based on your legal residence instead. This is a right of US citizenship; dual citizenship doesn't affect it. This State Department website has details; there's a special process you can generally use instead of the state absentee process. UOCAVA applies to all federal elections (including primaries); state and local election eligibility is up to the state.
For Canada, citizens of Canada living there seem to have the right to vote regardless of any possible loyalty issues with another country. Canadians living outside Canada for over five years can't vote, but if you live there it seems as though it is allowed.
So, the answer is seemingly "yes." For a definitive answer, contact the US consulate and Canadian election officials.