Guages Run Amuck!

1990 Ford Escort
1.9L CFI
3 speed automatic (upshift to 2nd and 3rd happens prematurely) Why?

In addition to the pinging problem, which after many weeks of diagnostics and tests I still haven't found the cause, I now have an intermittent fuel and temperature guage problem. At least once a day for no apparent reason, both guages will go up to the high or full position at the same time. At first, I thought it was the temperature guage sender. Today, I realized that if I tap on the clear plastic in front of the guages, they return to normal position. I'm thinking that it might be the IPVR (Instrument Panel Voltage Regulator) or a loose connector behind the insturment panel. Any help would be appreciated.

Gauges that do this..about 99.99% of the time it is a poor ground SOMEHERE along the line.Best is to simply take the gound off..cut/strip the wire..chan the connector..and clean the ground area if need be.Or.run an additional ground wire.All too often they LOOK ok..and there is such a miniscule amount of current/voltage involved.that there is JUST ENOUGH ground at times to allow them to work..a few good strands left/bent in such a way etc.,taking these off..or a light pull.. often shows a good strand or two left and the rest just falls apart as corrosion/powder.