US citizen working in US but living in Canada

I am a US citizen and PR of Canada i would like to live in Toronto to take care of my grandmother who is ill my mother lives in Toronto as well i come to Toronto when ever i am off i am a pilot can i live in Toronto and work in the US.

Provided your PR status is still valid. As said, it's two years out of every five you have to be in Canada to maintain it. CBSA will quiz you about this at the POE when you bring in your personal effects, because it will look odd to them that someone with LPR status for so long wants to bring in personal effects. If you try and get around it by lying and saying you've lived in Canada for x time, then they will charge you duty and GST on your personal effects because technically you're saying you reside in Canada.

Remember as a US citizen you still have to file a 1040 every year and a 2555 (or 2555-EZ as the case may be) as well if you reside in Canada.

The 2555 is not mandatory. The 1040 is, and one can use 1116 instead of 2555. 1116 reduces income tax to zetro in any event, and allows one to claim the child tax credit, which 2555 does not.