For fuel economy, dump the auto and get a manual box. Dump the drive line oils and go for lighter viscosity oil grades like SAE90 or even SAE85 if your diffs aren't too worn. Also, the 1KZ in the Prado comes with 4.3 diffs, your vehicle probably has 4.11 diffs. You might want to look at this as well if you want zippier acceleration/power off-road. Might also help with fuel economy since the engine will rev more freely and lug less and you will be pushing down on the accelerator lesser. Other than that, there's nothing much you can do with an EFI IP. As for the suspension, well, you might as well destroy it yourself than to travel all the way to Peshawar or Pindi for getting it coil sprung. Leave the leafs be and adjust the spring rate/steps for a softer ride. They don't ride too bad when set up right and have decent flex.