91 explorer runs rough, eats gas

So far I have replaced plugs, wires, fuel filter, and air filter. I removed the cat converter cuz it sounded like it was plugged. It was not. Still runs like crap. I can pull each plug wire and get a change in RPM. I can pull each fuel injector connector and get an RPM change as well. The only code I get is a secondary electrical system for the fuel pump. Not sure what this is telling me but my pump relay has a short in the harness that will kick the pump on when not running every once in a while. (door slam) Any ideas out there?

Low fuel pressure can be an issue as we tend to further screw up the air fuel mixture by pressing on the gas thinking we are coaxing more power out of it. You definitely shoul fix this problem regardless if any other issues are found.

A 17 year old vehicle could have a very stretched timing chain. I have changed small block Ford chains with as low as 75,000 miles.

One way to check the slop in the chain is to remove the distributor cap. With the key "in your pocket"rotate the crank shaft clockwise by hand until you reach 0 deg top dead center. Mark where the rotor on dist is pointing on the body of the dist. Rotate the crank counter clockwise while watching the rotor. As soon as the rotor starts to move, stop turning the crank. Read on the balancer how many degrees you are away from 0 deg TDC. If it has moved more than 3 degrees, you need to change the chain and gears.

Good idea but my Explorer don't have a distributor and rotor. Guess I could watch a rocker arm with a valve cover off.
As far as the fuel pump electrical code, the tester won't give me codes now, won't re-test.
????