Well K-Jet FI high fuel consumption is such a combination of worn things. An often overlooked part is an old fuel accumulator whereas the old diaphragm leaks so system pressure is not the dead stable and correct, and people try and compensate at fuel distributor shim.
Other factors: worn uni joints and centre bearing, transmission fluid, worn trans / torque converter, worn diff, worn engine, often dragging brakes as piston(s) not springing back due to clogged up with brake dust, the list goes on.
And how much you have in the boot that you drag around. And the tow bar. I know two owners and their boots are so full of heavy spare parts its no wonder fuel consumption has increased.
Quick improvements: higher tyre pressures and if due a trans fluid change. With the high compression B23F 98 is better than 95 but its what suits your curcumstances.