I had a fluctuating gauge reading on my 300E and solved it by adding a loop of thin solder to the temp. sensor post to make a very solid physical connection to the press-on connector. It cured it! There was just too much mechanical slop in the connection.

__________________
'76 240D-Sold
'78 240D-Sold
'85 300 SD, 165K-Sold
'88 300 TE, 165K-Sold
'64 Porsche 356C Cabriolet- under restoration
'86 560SL 124K Miles-Sold
'94 320E Wagon, 74K Miles-128K Miles JUNKED
'06 E350 Wagon, 84K Miles
07 SL550, 14K Miles