I know all 124's seem to have problems with cruise controll but mine will work but it speeds up then taps off then puts full throttle then taps off....you get the picture but all my friends think its hilarious, I take that its reading incorrect speeds? What part needs repairing or replacing?

Secondly earlier I posted a a thread but I can't find it but it was about what I thought was low voltage becuause instrument lights and cubby hole lights etc.. are all dimmer than other 124's but the voltage reads 12.something when off and 13.68V when running, even across the battery so its then exactly right?