injectors or what

hey guys need some help,have a 02 4x4 3.4 auto, was in mexico and got some bad fuel, have run two tanks of fresh fuel with lucas fuel cleaner, but now i get a backfire off idle, runs good at highway speeds but not reving up as fast as before, changed fuel filter, plugs are new, cleaned k@n filter, can the timing be off any ideas

 

Lucas fuel cleaner is not doing anything.
If you got a truly bad tank, it's going to take more than 2 tanks to flush it out... Best to remove the tank, clean it out, and purge the system with known-good fuel.

A tank of bad gas would not have changed your timing... don't mess with anything that's not directly related to the fuel system or you add to the confusion if/when you end up taking it to a shop.
Fuel problems causing an erratic idle can appear to throw the timing off, but that's only because of the inconsistent idle and vacuum.

 

backfiring can mean it running too lean, and it will RUIN your cats.
drop tank, clean, blow out fuel lines, change filter.
and the strain on the fuel pump will burn it out, or shorten its life.
and there is a pre filter on the fuel pump, not sure on some cars its all one piece, dont know if you can buy a new prefilter, but that will need to be looked at also.
and the trash and water will corrode and ruin your fuel injectors. or clog them up. they can burn out also if clogged up. it puts a bad strain on everything...