Intermittent guage problems? Engine knock?
 

On 2 occaisions over the past month, with an almost empty gas tank, my fuel guage began creeping upward until it showed full!? The guage stayed there until I turned off the car, and best I recall it went back to normal. The first time I immediately filled the tank and the the guage responded correctly while filling and operated OK for a month.

Today, my tach suddenly went to zero while driving home from work (about 10 minutes into a 30 minute commute) but all running fine. I initially suspected a related guage problem, however I also noticed the engine knocking/pinging somewhat while climbing a slight grade. Been so long since I 've driven a car with engine knock that I barely recognized it. This was a hot day (93+), first one in a while.

Any similar experiences or clues?

Got any Shell supplied gas lately? They had a large batch of high sulfer gas cause problems with fuel gauges.