2004 GMC Envoy XUV/ V8 / 112,000 miles The gauges on my truck are going crazy. The speedometer starts at 60 and is at 120 on the highway, Gas gage spins around 360 degrees, tachometer reads 7,000 then 3,000 then 6,000. It changes everyday. Sometimes its a couple of gages sometimes its all at once going crazy. Also, when in drive and at a red light the truck idles a bit rough. Kind of lopes the the point where it has to be put into neutral and the gas pedal depressed a bit to level it out. Thanks for the help in advance.