After thinking I had solved my particular variety of limp mode problem with the pressure relief valve "plug", I was wrong. Traveling in this springs higher temps, it was back with a vengeance. On the relatively short trip from Woodstown, NJ to Harrisburg,PA in May, the old truck fell into limp approx a dozen times. Oddly, not full blown 30mph limp, but around 50mph semi-limp. So I guess the plug was doing something, but I knew this truck was not making it back to Colorado.

I've sunk enough $$ into this truck for this and other issues. And after all it had 280k miles so I decided it was time. I traded it in. It will still make some farmer or kid a great daily driver, its just that its days of towing 14k were over. Here's hoping I don't re-visit the issue with the new truck!