Since no one knows/responding... It's Jack Morris.
It finally occurred to me what happened: Detroit had used pinch hitter Larry Herndon for the DH Dave Bergman. By taking out Herndon, the Tigers would lose their DH for the remainder of the game. I suppose Sparky did not want to lose another potential bench player in the event the game went into extra innings.
They would only lose the DH if they moved Herndon to a defensive position.Grubb, Heath, Madlock, and Morrison would have still been on the bench when Morris pinch-ran.Morris also had 2 pinch running appearances during the 1987 season, and 7 in 1983 and 8 in 1980! But only one other pinch running appearance outside those 3 seasons that I can identify (1979) from B-Ref (although it wouldn't surprise me if those records weren't complete).
The Tigers did lose the DH late in Game 2 that series, with starting catcher Mike Heath being removed for pinch hitter Johnny Grubb, and DH Matt Nokes shifting to catcher in the 8th inning. Interestingly, since no relief pitcher was used, starter Jack Morris was simply inserted into the lineup in Heath/Grubb's spot in the middle of the 8th inning (and did not wind up taking a turn at bat).