Nonsense. Both Harper and Mulroney were impacted by what happened in the US.

 The first Trudeau managed a operating loss  which Mulroney fixed but was over whelmed by the Paul Volker interest rat hikes of the early 1980's  largely because the first Trudeau left a huge deficit. The following Liberal government benefited from the implementation of the GST and falling interest rates.
Harper with the approval of the opposition Liberals and NDP  ran deficit to fight a US created recession. He balanced it after a few years. 

In both cases it was nothing the conservatives did. Both Trudeau's ran huge deficits for no reason.