My 2002 gmc envoy will start and run but dash is out, all digital dispays are out and radio and heater gauges flash intermittently headlights are dim turn signals do not work , turn key off and car stays on and hard to shift out of park any answers or has anyone had this happen?

Good golly ... what a collection of problems. Don't know the answer, but any time I have weird, seemingly disconnected, electrical problems I always start with checking the battery and charging system. A weak battery or under-performing charging system can cause all sorts of electrical problems.

I replaced Alternator and the Battery and its still doing same thing..

Sounds like an ignition switch problem ??????

Your ignition switch is either the 10 pin or 14 pin connector.

With vehicle running, wiggle the ignition switch connectors. If anything changes, replace the switch harness

I agree with the ignition switch, especially if you have transmission shifting problems, if the tranny is defaulted to 2nd or 3rd gear...

Can check for power to all fuses with a test light....if you have a series of fuses with no power to them, chances are it'* the ignition switch....