try running some fuel system cleaner, you know the stuff, any brand, through your tank. There's trouble with that MMTE fuel additive the oil companies put in during refinement. it coats the variable resistor for the sending unit, but usually, if you change fuel brands, run the cleaner, and maybe about 3 tanks of high grade, you're good to go. or else its the sender
(It's a GM secret bulletin remedy...)
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I'd rather be demolition derbying (yes I know that isn't a verb)