THIS PAST SUMMER IN JUNE, THE SPEEDOMETER WOULD READ 40-80 MPH WHEN STOPPED/IDLE. PROBLEM SUBSIDED AFTER A FEW WEEKS. MORE RECENTLY, WITHIN THE LAST 2 WEEKS, MY SPEEDOMETER IN MY 2005 IMPALA WOULD GRADUALLY GO DOWN GRADUALLY DURING LONG DISTANCE TRAVEL (100MI+) ON THE I-10. TO ME, THIS IS A VERY DANGEROUS ISSUE WITH THE CAR. *TR