Mechanics

I HAVE A GRAND CARAVN SXT 3.8L. RECENTLY, THE TACHOMETER HAS HAD A MIND OF ITS OWN WHILE DRIVING AND YOU CAN HEAR/FEEL THE VAN REVING UP/DOWN. NOW THE SPEEDOMETER DOESN'T CHANGE. SOMETIMES IT HAS DIFFICULTY SHIFTING WHEN THIS HAPPENS ALSO. ANY

2008 Dodge Caravan • 76,000 miles