My guage floats all over so Today I got under the car and puled the connectors around the tank.The first was next to a black box with a fuel line running out of it and the other 3 were next to that.All I did was disconnect each one and spray the plugs with deoxit and plug them back in.I know the guage SHOULD be reading less than 1/2 as I have OVER 200 miles on the tank right now but now reads above full? Whats up with that? Also,what is that black plastic box under the tank with the fuel line coming out of it?Which plug is the guage? The one in the box with 2 wire?

Your car may have a splash module which is worn out. It is usually under the dash. The reason you are getting a different reading is that your module is confused and worn out.

Could you be more specific?What does it do?Where exactly is it?How do you test it?