Mulroney incurred deficits - even with operating surpluses in 5 of 9 years - after Trudeau 1.0 stuck him with a national debt that took 30-40% of the annual budget just to pay the interest on PET's debt.  Only savage cuts to federal programs and individual and provincial transfer payments would have avoided deficits at that point and the Liberals who created this crisis went ballistic when Brian proposed even modest cuts.

Chretien/ Martin did balance the budget finally after increasing pressure from the IMF.  They were able to do so for two reasons.  One was that Mulroney's NAFTA and GST reforms by then made a major difference in increased federal revenues and lower interest rates reduced servicing costs.  The other reason was the opposition was in total disarray so the Liberals felt free to impose substantial cuts.  Not to their own spending, of course, only 2% but to provincial and individual transfer payments.

Liberals own this 70s-90s crisis.

And the new guy is scary indeed.