So, as I feared, the truck is still struggling to maintain highway speeds with erratic engine load. Watch the video on 1080p..you can probably hear the truck revving and dropping, but even if not, you can watch the engine load on my obdii cell phone in the top left gauge (shout out to moparman for sending me his obdii gauge file a year ago) and you can see the needle all over the place trying to maintain speed. 0-52, 25-50, etc etc..it's revving hard, dropping, revving, dropping. She as it used to. 

 

 

One curious thing I noticed while doing all that electrical stuff..is there seems to be a random wire, probably #18, going from a body mount in the front, grounding on the body in the same spot as a probably #8 ground coming off the driver side negative battery terminal. First pic shows location, second, you can see it heading into the apps loom. (I didn't know how hot that black plastic tube got, so I put some spare loom around the battery negative and the #18 wire)

 

Is this little body mounted ground to tps factory? It doesn't feel seem like it. Could this be part of the problem? 

So I'm getting really weird voltage drop, truck is hesitating to start a little bit..I'm seeing my voltage drop completely to under 12v, like the alternator just isn't working. Could this be because I don't have a wire from pdc to passenger? I can't confirm right now..but I think my driver side battery isn't charging. It's raining and I'm not at the house to check it's voltage..but I did see the voltage drop big several times..like to under 12v, almost like the grid heater was running of battery alone. That's not grid heater dropping it that hard, is it? Truck has always started strong..I'm thinking I've got an issue. 

Possibly the grid heaters pulling hard? Go drive the truck and get above 25 MPH and check the voltage again.