Accelerator pedal position sensor?

P2138 means the PCM sees the two accelerator pedal position signals not agreeing with each other. Some after market parts are junk right out of the box, I would try to get a OEM unit by searching ebay, also please inspect the electrical connector for damage. Here is a guide to help test the wiring and the diagrams for the wiring that goes to the PCM.

https://www.2carpros.com/articles/how-to-check-wiring

Check out the images (below). Let us know how it goes

I tested the resistance on the pedal itself, on sensor 1it showed 2.1 and on sensor two it showed 2.87.
Then I checked the 5V ref on both sensors and it was good. I then checked both ground wires and they were good. Then I checked sensor 1 signal wire and it read at pedal rest 1.0 and then all the way to the floor was 4.1
on the instructions it said at rest 1.0 and to the floor 2.1, so could this be a problem.

Yep, this means the pedal sensor is bad, I would get an OEM unit from ebay.

I have now tried 5 accelerator pedals with sensors, 3 were aftermarket and the other 2, I have bought used on ebay, they are OEM though. I have check the wires for power, ground which checked out ok. But all 5 pedals when checking the signal wires for sensor 1 show starting at 1.0 and goes to 4.1, Sensor 2 shows 0.50 to 2.0, each time it set code p2138. I have tested the signal wires for sensor 1 & 2 back to the x111 connector for continuity, that check out ok.
I haven't went all the way to the ECU yet. I wanted to see if you have any suggestions on what to do next? Thanks!

Nope, we did everything to test, the ECU is next. Let me know, that should fix it.

update: I started testing the wires and connections from the ECM to the APPS and in the process the battery voltage dropped while testing and that started a tailspin. I have a code U0100, I have dash lights when I turn it to on, but the car will not start. I have checked the fuses and relays in the fuse box. Don't see any problem there. What would you suggest I Check first to see if I can get the car communicating again. ( I have charged my battery, but I thinking about buying another one.) Can you keep a battery charger connected while running diagnostics?

When you charge the battery and remove the leads after the charge is done what is the battery voltage?

it shows around 12.6 or a little higher after charging, but the voltage starts dropping quickly once I turn the ignition on. I checked it within about 5 minutes and it showed 11.89. the day it went down it really drop and the dash lights starting flashing and the steering wheel wouldn't let me take key out. Then I charged it again and check for codes with the scanner and that's when it gave me the code U0100,

Yep, these are signs the battery is no good which will give you the code as well. I would get a new battery and clear the codes. Please let me know what happens.

update: as stated before I was testing from the ECM to sensors and the wiring in general, the power dropped from a bad battery. setting off the U0100 code where it was not communicating with the ECM and causing a no crank, no start. So I tested the CAN BUS + AND - and discovered that the terminating resistor at the ECM was bad. So I'm going to buy another ECM. I'm hoping that will getting the car running again and Help address the original problem with the trouble code P2138 with the APPS and the car going into Limp mode.