I don't know about everything else but the gas guage problem is probably you fuel sending unit if Im correct with the wording. I had the same problem where I turn the car on and it would go to empty but I turn the car back off then turn it on again and the gas guage would go back to the correct gas level I had in the car.
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Exterior- stock painted black wheels, clear corners, stainless steel grill, cross and drilled front and rear rotors with evolution brake pads.
Coming soon- 18 inch black mustang bullet rims, GT/GTP rear bumper, tinted windows.