The Hammers almost blew a 3-0 lead against Leicester, as they did against Arsenal recently.
And Moyes acknowledged he must fix the worrying pattern as West Ham look to secure fourth-place on the table.
"I'm not smiling," Moyes said after the game. "This one is a stick-on smile today. This is a smile of anger because we nearly threw away another big three points for us and we don't want to do that.
"We were 3-0 up against Arsenal and 3-0 up against Wolves and 3-0 up against Leicester and they're incredible results, but they don't sound that incredible when it goes 3-3, 3-2, 3-2.
"I've got to try and put an end to that. I can't allow that to happen and we've got to be better."