AT 70 MPH VEHICLE SLOWED ON ITS OWN. VEHICLE INFORMATION CENTER READ "STABILITRAK AND ENGINE POWER IS REDUCED". GOT YELLOW TRACTION CONTROL SYSTEM LIGHT ON THE INSTRUMENT PANEL WITH A "MALFUNCTION INDICATOR LIGHT" BELOW THE SPEEDOMETER.ENGINE RUNNING ROUGH AT ASHLAND, VA EXIT.ENGINE WAS SHUT DOWN THEN RESTARTED WITH SAME WARNINGS AS BEFORE.APPROXIMATELY 45 MINS LATER RESTARTED TO HAVE A LOCAL CHEVROLET DEALER LOOK AT THE CAR. ON RESTART, ALL WARNINGS AND INDICATOR LIGHTS EXCEPT FOR THE "MALFUNCTION INDICATOR LIGHT" WERE OUT AND ENGINE RAN NORMALLY.DEALER GUESSED THAT IT WAS PROBABLY A "GLITCH" AND IT WAS PROBABLY OK TO DRIVE.THE 800 OR SO MILES TO SARASOTA WERE WITHOUT PROBLEMS. ON 8/5/2013 TOOK CAR TO LOCAL DEALER APPROXIMATELY 3 MILES FROM MY HOME. ON ENTERING THE DEALER'S PARKING LOT AT APPROXIMATELY 10 MPH THE PROBLEM REAPPEARED I.E. "ENGINE POWER REDUCED WITH STABILITRAK" WITH WARNING LIGHTS AS BEFORE. THIS IS A SAFETY ISSUE AS IT CAN HAPPEN AT ANY TIME!! *TR