The Trail Blazers owned a 20-point lead heading into the fourth quarter only to have the Pistons close within two on a tip-in by Charlie Villanueva with 15 seconds to play.
Blake made his foul shots for a four-point lead with 10 seconds left and Miller converted two more with 5 seconds remaining.
Portland bounced back from its first loss in more than two weeks. The Trail Blazers suffered a setback in Atlanta Monday after winning six in a row.
Brandon Roy and LaMarcus Aldridge both scored 20 points and Blake had 17 for Portland, which moved into a tie with Denver atop the Northwest Division.
Rodney Stuckey led Detroit with 21 points and Villanueva had 20.