dealer has checked and wiring ok,dealer replaced encoder motor.4x4 problem still exists.

GM dealer checked for shorts ,loose wires behind dash ,scanned for other problems and resets 4x4,button lights come on 2h 4h&4L,shift to 4h and go a few miles service 4x4 comes on,buttons go off.

full tank new fuel filter new fuel pressure regulator but still staling when I go stop or turn.GM did a injector flush and new plugs. still have problems. light still comes on code is PO171

when cold, the engine acts as if it is starving for gas for about a mile. then it runs fine until it sits over night.

The aux. power re-engages after the key is removed from the ignition. This may happen immediately after removing the key or up to several hours later.

When I'm driving I hear a high pitched noise coming from the front wheels but stops when brakes are applied, what could be causing this and how do I go about fixing it's?

I just changed my clutch and put everything back the way it came out. Now my service 4 wheel drive light is on. I did notice some small scrapes in the wires going to the sensor on the bottom of the transfer case.

Bought truck from car dealer was Maryland inspected and 7 months latter frame rusted thru holes big enough to stick 4 fingers in and cracked so bad can not be driven. 107000 miles body in great condition no rust, only frame.

where do i begin to sovle this issue