Ωhm

You going to need to look in the harness loom near where the ballast is. Your looking for the Orange wire (fuel pump circuit) to determine if someone bypassed the ballast (two orange wires solder together) or is it a solid wire. Solid wire would mean more work would be required involving the O2 Heater Relay.

Backprobe the TPS (KEY ON: pins B & C) at both Closed Throttle (CT) and Wide Open Throttle (WOT) (note voltage readings) using the gas pedal. Take the same readings with gas pedal disconnected and manually move the throttle between the stops. Compare the voltage readings taken. Should be the same.

Pegged FULL fuel gauge: -Faulty gauge -Open circuit -Check switch on Parking Brake -Faulty brake system -Disconnect connector at parking brakes and see if problem goes away. Check for faulty switch on 4WD unit.

Start with the battery cables, plus and minus, engine block ground, battery plus to starter relay and all the fusible links.

Sounds like good advise here.

I would think the KS is a finely tuned circuit to a specific location.

Is this just a idle problem. Does engine smooth out with higher RPM's?

That's the way to go for the red lens. Replace both lower single filament with a dual filament and wire it just like the MJ. Low intensity bulbs for running/taillights, high intensity bulbs for (L/R) brake/turn/hazard.

Optional choice over the Standard REM.

https://nickintimedesign.com/

Buy a REM (Renix Engine Monitor).

One (1) picture is worth a thousand (1000) keystrokes. OP said he's rewiring. I can't tell where the MJ harness ends and the Ranger harness begins.

Just a thought, but what if you have a sluggish starter relay or sloppy ignition switch.

The 1156 is a high intensity filament. This bulb should parallel the high intensity filament of the 2057 (Brake/Turn Signal/Hazard). Do you plan on keeping this as part of the wiring? If so, why?

Should also check the connector from the engine harness to the front lighting harness. Cruisers tip shows what you don't want. http://cruiser54.com/?p=35