I have just acquired a 1995 SL 320 and when driving it home the speedo was jumping all over the place at lower speeds. Once cruising on the motorway at above 50mph it seemed fine. Anyone come across this before and know what the issue might be? There are no other warning lights on although the accelerator pedal is very stiff! The car hasn't been driven much in the last few years and not at all in the last 6 months. Any help much appreciated. Thanks