I sent you a PM, but I'd say your FCA is faulty, or possibly the RPS. Any codes other than the ABS?

 

The first I thought of when you said it was dieseling was the FCA. The FCA went bad in my 03. I drove it home shut it down and it was running fine. Went back out to start it, and it sounded like a 12 valve. Took it to the dealer and it was the FCA. I had a load of bad fuel that didn't help it any either. I hope you can get it figured out.

Marshall

 

After much diagnosis I decided to order a fuel rail pressure sensor. Put it in and truck runs great. I also mounted a frame rail airtex diesel rated fuel pump. As well as confirmed that this truck indeed did not have a lift pump.

I am so happy the rest of the injection system was fine.

Thanks everyone