My '97 Jimmy has had an inaccurate gas gauge for several years now. Initially, it would read accurately until approximately 1/4 of the tank of fuel remained. After this point it would read full regardless of how much gas was in the tank. Over time this has progressed so the gauge only reads accurately until approximately 3/4 of the tank of fuel remains and most of the time the gauge reads full. I have simply been refilling every 200 miles during this time but I have forgotten a few times and been stranded so I would like to address it now. The gauge needle also oscillates in time with the turn signal when it is activated which may or may not be related. I am having no fuel supply issues so I don't think there is an issue with the fuel pump but I believe the pump and fuel sender are integrated in my model year so it may be necessary to replace it anyway. Any insight or guidance would be appreciated.