The biennial budget Gov. Dannel P. Malloy intends to propose today would erase a two-year, $2.5 billion shortfall with $1.6 billion in spending cuts and $900 million in additional revenue, an attempt to say he is equitably spreading pain while keeping a pledge not to raise taxes. Malloy, a Democrat re-elected last fall, is proposing a three-pronged approach to his second fiscal crisis in four years: deep spending cuts, combined with additional revenue raised by deferring promised tax cuts and boosting tax receipts without changing rates.