1999 Chevy Malibu 1999 Chevy Malibu - Hesitation/Fuel Gauge

My car has been having troubles that are getting worse as it goes. If I get below half a tank, my gas gauge drops down to empty, dings, and the light goes on. If I stop somewhere and restart my car, the gauge sometimes jumps back up to above 1/2 a tank or sometimes up to full and then drops down from there.

Also, my car has been hesitating when I try to accelerate, especially if driving above 50 or so on the highway and having to slow down. I can feel it kick in and then accelerate especially if RPMs drop below 1500.

I've also had an issue with my car shutting itself off. This happens mostly when I have to brake quickly and go over railroad tracks or it happens mostly when I have to brake and then make a turn (mostly right turns). My battery and the light next to it come on and I have to stop and restart my car and it seems to run okay from there.

I know it is a lot going on and I'm tired of putting money into this car but at this point I don't think I can afford a new one so gotta fix what is wrong.

Thank you for any help and advice you can give me!