After installing a lift, larger tires, new gear ratios and adding more weight from armor or cages can affect your gas mileage.
84-86 were carburated chevy v6's
87-90 were renix fuel injection
91-01 were chrysler fuel injection
Fuel Gauge Issues
Fuel gauge showing opposite fuel levels
If your fuel tank is actually empty but the gauge shows as full and when you fill up your tank and it shows as empty, this means you picked up the wrong fuel sending unit.