2006 PORSCHE CAYENNE Engine And Engine Coolingengine Problems

VEHICLE RUNS INEFFICIENTLY WHEN COLD AND SMOKE HAS BEEN NOTED FROM THE EXHAUST PIPE WHEN VEHICLE IS DRIVEN. IT WILL TURN OVER, BUT NOT CATCH. DEALERSHIP WAS TOLD BY PORSCHE TO USE A LOWER OCTANE FUEL (87) TO REMEDY THE PROBLEM. THIS CONTRADICTS THE INFORMATION IN THE OWNER'S MANUAL WHICH STATES ONLY PREMIUM UNLEADED FUEL 91 OR HIGHER SHOULD BE USED. IF THE VEHICLE IS TAKEN INTO A LOWER ALTITUDE AREA, THE FUEL SHOULD REVERT TO PREMIUM. THIS IS A BRAND NEW CAR AND IT DOES NOT START WHEN THE ENGINE IS TURNED OVER, LEADING ME TO BELIEVE THERE IS A MANUFACTURING DEFECT IN THE DESIGN OF THE ENGINE. MY HUSBAND OWNS A 2004 CAYENNE S, WHICH HAS A 4.5 V-8 INSTEAD OF THE 3.2 LITER V-6 AND IT STARTS IMMEDIATELY, EVEN WHEN COLD. *NM

VEHICLE SUDDENLY LOSES POWER ("THROTTLE CONTROL" AS THE SERVICE REP PUTS IT), USUALLY WHILE TRAVELING AT HIGHWAY SPEEDS. THIS CAUSES SUDDEN DECELERATION, CREATING ISSUES FOR SURROUNDING TRAFFIC. IN EACH CASE IF I FLOOR THE ACCELERATOR I CAN MAINTAIN APPROXIMATELY 25 MPH TO GET TO A SIDE STREET, WHERE I ARRANGE FOR A TOW TRUCK. THIS VEHICLE HAS BEEN IN THE SHOP THREE TIMES FOR A TOTAL OF A MONTH, DURING IT'S FIRST 6 MONTHS (14,000 MILES) FOR THIS CONDITION. EACH TIME THE PORSCHE DEALER BELIEVES IT HAS BEEN FIXED. INTERMITTENT SO HARD TO DIAGNOSE. *NM