First off I apologize for posting so much as this is my third post in a few weeks, I got my 03 drive train running and and and working as it should but it idles really low ( 400-600 rpm ) and really really rough, no misfire , and smoothes up really good and drives down the road good, also holds the rpm when you pull it into gear ( doesnt die ) I'm getting 8 02 codes all saying 02 sensor heater bank 1 sensor 1/2 , codes 135, 141 and 155 are all 02s and code 131 that's just coming up manufacture control

 

For 2003 Ranger check Fuse 41 in engine bay fuse box, 20amp, that powers the O2 heaters, TEST IT or swap it don't just "look at it"

The 12volts from fuse 41 flows thru all 3 O2 heaters, TO the computer, so computer is the ground for the heaters and so the computer can tell if there is no 12volts to each heater when key is on
So either all 3 O2 wires are unplugged or fuse 41 is blown

Fuse 41 also powers transmission solenoids if you have an automatic, so shifting should be abrupt, if a manual then wouldn't matter

 

That actually makes sense , the drive train is currently in a 98 model that was previously a straight drive, ( swapped ecu, auto trans motor ect ) any idea what wires may lead to that fuse? The 98 has a slightly different fuse box

 

Also the trans does shift hard and abruptly, and is also worth noting that we did not swap the inside wiring harness ( inside the cab ) only plugged the engine harness into the existing 98 model harness,

 

In 1998 its fuse 13 in engine fuse box, 15amp

Light blue/orange stripe wire runs from that fuse to transmission and the O2 sensor connectors, not the O2s, O2 wire colors are different
Its also use to power EVAP canister vent solenoid, and EGR solenoid
All use the light blue/orange colored wire, so if new fuse blows with key on start checking for the short