Atiba Harris gave the hosts a 56th-minute lead before Blas Perez levelled the scores. Harris put his side ahead once again three minutes later, but the Rapids were to be denied once again when, just two minutes after they had fallen behind, Perez notched again.
Jamison Olave saw red as the New York Red Bulls were beaten 2-1 by the Vancouver Whitecaps in New York.
Greg Klazura put through his own net to give the home side the lead early in the second half before the Canadians equalised after 59 minutes through Jordan Harvey.
Olave was given his marching orders and Vancouver took full advantage with Kenny Miller scoring the winner seven minutes from time.
A goal from Obafemi Martins (22) and an own goal from Mario de Luna just after the half-hour mark saw Seattle Sounders to a 2-0 win over Chivas USA, who remain bottom of the Western Conference with just three wins from 13 matches.
Columbus Crew and Houston Dynamo played out a 1-1 draw with Warren Creavalle's 31st-minute opener for the visitors cancelled out by Federico Higuain's 69th-minute penalty.
First-half goals from Javier Morales (16), Ned Grabavoy (33) and Robbie Findley (38) saw Real Salt Lake to a 3-0 win at home to San Jose Earthquakes.
Montreal Impact recovered from going behind to a Claudio Bieler penalty four minutes into first-half stoppage time to win 2-1 through goals from Sanna Nyassi (48) and Collen Warner (53), despite having Alessandro Nesta sent off with 15 minutes remaining.
Jack McInerney scored in the last minute to rescue a point for Philadelphia Union who drew 1-1 at Toronto after Jonathan Osorio scored the opener on 66 minutes.