Had a few threads on this... not getting anywhere sadly.

Initially figured it was a throttle body deal... had the error come up and engine shudder and shut off. I cleaned the TB and it ran fine for a few days then did it again. Grabbed a TB from the wreckers, worked a few months then did it again. Bought a new TB and lasted a few hours and got the error again.

I have a 2003 Laramie 5.7l Hemi 4x4, and for 2003-04 of this model, the Accelerator Pedal Position Sensor was below the battery tray. No longer made, NOS is around $650USD and I'm in Canada. Finally found a local(ish) wrecker with what I needed. Grabbed the APPS, cleaned the contacts with contact cleaner, and at the same time the plug for it as well as the contacts/plug for the TB. Installed it, did the reset and worked for a week.

By this time, my truck has sat around over a year total because can't work on it in the snow and various back related issues.

Drove it today, first time in a few months (needs brakes but want to drive it to keep this from seizing and battery charged) and 20min to town, grabbed a coffee, 20min home, city/highway driving... ran perfect. Then in my driveway I did a 3 point turn to back into it's parking spot and while in reverse, yup... that damn red lightning bolt and everything shuddering again.

What's left?

 

PCM stock tuned? Some tuners will trigger throttle issues. Not as common as you seem to be experiencing, but I've had it happen maybe a dozen times on my last truck (04) with a superchips. Running fine for a few days might also indicate that your manipulation of the harness in and around the throttle body might be a clue.

Verify all grounds and current carrying capability of said grounds at the throttle body. As it's a plastic intake, it has no natural block ground.

 

As far as I know it's stock... But the previous owner did a few things to the truck, so maybe not.

I often wondered if the remote starter he added may have been done wrong. Remote is busted so no idea if it even works but, I heard sometimes those aftermarket starters cause issues too.

 

Anything aftermarket like that can. Remove the system and go from there.

 

Other forum, guy popped up... grounding straps on the engine/valve covers were rotted and some sparking.... replaced and done.

Which, I did have a few weird sparks near the spot where the oil goes in and sure enough, just a nubbin' of a strap left... not sure where the rest went.

Problem is, I can't seem to find on parts sites the grounding straps, not even just to see how long I need.

Far as I can tell in diagrams.... I guess there is 1 strap connected between the two covers, 1 strap where the oil goes in which connects to the valve cover on the driver side. The post I saw said he also ran 1 more from that driver side cover to the metal body just to make sure it's grounded.

Sound right?

Any idea how long? Since mine's rotted and missing I can't measure it.

 

I just bought a 5-wire grounding kit off Amazon for $30CAD. 8AWG spool of wire was $35 plus needed the ring terminals and such. This was cheaper and easier.

Ran a cable from the passenger side valve cover to the driver side, and from that to the bolt behind the battery where it grounds to the frame, as well as a new ground from that to the negative terminal of the battery. Plus ran a cable from the alternator to the positive terminal (left original cable there). Not yet found the other ground, which I read was at the back of the engine block, but, just not found it it. Drove/Started fine today... fingers crossed.