One problem related to power steering fluid has been reported for the 2004 GMC Envoy. The most recently reported issues are listed below.
Was park, went to back up and felt like there was no power steering. Ps fluid is good, belt is good, pulley seems fine, no leaks, but very hard to steer. This 2004 GMC Envoy has been nothing but a headache. . . . Not to mention the speedometer doesn't work properly either.