How cold is it in Canada these days? Maybe that has something to do with it. Does it vary with operating temperature? Have you been parking inside so things can melt off the car?
I'd do a quick check for vacuum leaks just for fun.

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2001 x5 3.0 (sold with broken motor), 1990 e30 M3, 1991 318is, 2002 325i, 2008 335i Dinan stage 3 6 speed,