2006 GMC ENVOY XL Steering Problems

STEERING WHEEL LOCKS. IT CANNOT BE TURNED TO THE RIGHT AS IT WILL CAUSE THE ENTIRE CARE TO SWERVE. WHEN REVERSING THE CAR TURNS IN THE OPPOSITE DIRECTION OF WHERE YOU ARE TURNING. I'M BACKING INTO TRAFFIC AND HAVE TO MANUALLY PULL THE STEERING WHEEL AS IF THERE IS A POWER STEERING ISSUE. ENGINE LIGHT CAME ON DAY AFTER PURCHASE INDICATING I NEED CATALYST CONVERTER AND SENSOR. NO WAY TO PREDICT WHICH WAY THE CAR WILL TURN. IF I HIT A BUMP THE CAR SWERVES TO THE RIGHT CAUSING ME TO SWERVE INTO NEXT LANE. IN MOTION I AM CONSTANTLY SWERVING INTO DANGER.

WHEN TURNING CORNERS ON SMOOTH ASPHALT THE STABILITRAC LIGHT COMES ON AND ENGAGES THE SYSTEM WHICH CAUSES THE VEHICLE TO MOMENTARILY SLOW DOWN AND MAKES A "GROWL" SOUND, THIS ALSO EFFECTS THE STEERING. IT MAY DO THIS MULTIPLE TIMES PER TURN OR ONLY ONCE. IT HAS OCCURRED AT VARYING SPEEDS (TURNS AT 45MPH AND TURNS AT 10MPH). STARTED OUT ONLY OCCURRING DURING LEFT HAND TURNS, NOW HAPPENS ON ALMOST ALL TURNS. I HAVE NOTICED IT IS MUCH WORSE ON WINDY DAYS. THE STABILITRAC ALSO KICKS IN WHEN I TURN ONTO GRAVEL AND START TO SPEED UP (NOT MASHING THE GAS AND SPINNING TIRES, BUT SIMPLY SPEEDING UP AT A REGULAR PACE THAT SHOULD NOT POSE PROBLEMS). *TR