Hi Frank,

It's very difficult to analyse issues like that from afar, but it sounds like a half-broken wire to a sensor or a sensor that is faulty or on the way out. Best bet is to get the car along to a good mechanic and start by plugging it into a diagnostic machine. Even that might not pick up the issue of course, so leave the car with the mechanic for a few days to experience it for themselves.

Best of luck