problem with gas gauge on 95 Buick Lesabre

The other day I had an emergency and went about 95 mph to get where I needed to be, on the way my gas gauge started jumping a lot. It had around a quarter of gas and it jumps past full and down to empty and just keeps moving. The other day we replaced radiator because the head broke on it. could that have anything to do with it? What would I need to look at?

Response:
Your Fuel Gauge has a Fuse marked Gauges in your Fuse Panel and is also connected at the Fuel Pump Relay then 4 wires continue to the Fuel Cell. 2 wires go to the Gauge and the other 2 run the Fuel Pump. Check your connections under the hood but I believe you will find the short wire harness inside the fuel cell is making intermediate connections