Without an away win since November, Accrington hit Dale with a sucker punch in the 76th minute when Molyneux sent a thunderous 30-yard strike into the top right-hand corner of Josh Lillis' net. And he followed that up minutes later with a superb 25-yard free kick.
Romuald Boco added the finishing touch, netting a third in the 88th minute after Lillis had pushed James Beattie's shot onto the crossbar.
"I knew Lee had that in his locker, he's been patient and waited for his chance and that was just about the best 20 minutes I've seen from a substitute," said Richardson.
"We asked him to make an impact when we sent him on and he's certainly done that.
"They were three superb goals and sometimes you don't always get the rewards your hard work deserves, and I've felt that has been the case over the last month. But this win was reward for the hard work the players have been putting in.
"They had a lot of possession and played some nice football, but I thought we dealt very well with it defensively.
"This is only one win and the aim for us now is to get back-to-back wins. We've got a dozen or so games left and we now need to win the majority of those."