Inspecting Accelerator Pedal Position (APP) on 98 Chevy Silverado

First time post - I just recently got my first diesel and trying to learn as much as so can!

As I was driving to work this morning, I hit a smaller-sized pothole and then the “Service Throttle” light came on and I lost all acceleration. The truck continued to idle, and thankfully I had enough speed going to pull off the road and out of traffic. I turned the truck off and right back on again, and there was no light - everything was fine and I made it to work. The light hasn’t come back on.

After this happened, I also remembered there have been times when it seemed like the truck accelerated on its own - a couple of times when I’m reverse - but I figured my foot must have slipped those times. But after this morning, and doing some research on the APP, I’m wondering if it’s all the same issue.

I haven’t had time to inspect the APP yet, but I’m planning on it today/tomorrow. The main thing I need help with (for now!) is to figure out where the ground is connected for it. I’ve got a 1998 4dr Chevy Silverado. With what I’ve read so far, I’m going to check the wire harness/pins for corrosion and then make sure the ground has good contact - but I have no idea where the ground is located to check it! Can anyone help me out?

Thanks in advance!