I.e. the wiring in the gas tank....The problem would be constant, and just not when the car is in motion.
Also I think the problem would be of a different nature, moreso the sender reading either constant empty (no output), or being stuck at a fixed reading, regardless of the level of gas in the tank.

Chances are you have a bad ground somewhere. I would check the sender, using the VOM meter....

Now the connection could be loose anywhere between the sender and the gauge, inlcuding the acutal gauge.... To see if the sender is faulty or having the wiring problem, have someone drive the car, while you have the VOM connected to the sender, and see if the reading of resistance jumps around. If the sender output remains steady (with slight variation from incline and gas moving around in the tank) then the problem is on the gauge side. - The gauge could be failing, or have a loose connection at the cluster.

I'm thinking something is loose and causing an intermittent connection, most likely a ground screw that has somehow vibrated its way loose.

__________________
George Androulakis

Former Mb's:

1990 500sl R129 - 76k Original Miles - New project - Follow the saga http://90r129.blogspot.com/
1990 190E 2.6 148k mi (sold)
1989 420 SEL 246k mi (sold)
1995 C220 175k mi (sold)
1992 190e 2.6 74k original miles (sold)
2000 c230 Kompressor 122k miles (RIP)
1996 C220 149k mi (sold)
2000 C230 Kompressor Sport 127k (sold)

Current Cars:

2009 Mercedes c300 4matic
2006 Mercedes s430
2005 Jaguar XJR
2003 Cadillac Escalade