1994 E-500..the temp gauge of external ambient temperature started giving readings approx. 20 degrees below the actual temperature outside ( ex. if it was 39 degrees outside it would read 19 to 22 degrees on the gauge). Curiously, if I,ve gotten in the car after it has sat overnight the temp gauge reads normally, however within 2 minutes it starts giving the wrong reading. I,ve replaced the temp sensor wire to no avail. I can't believe it is the display module as it gives an accurate reading for brief periods of time. Suggestions?