Nit is right, pulling codes would help.
A possible issue could be low oil level (cut out on a hill). Not saying that's your problem but it's worth checking. These trucks use high pressure engine oil to inject the diesel fuel. So if you don't have enough oil, you won't be injecting much fuel and it will run rough, maybe smoke and have no power at all.
Hope this helps.
Lou
A possible issue could be low oil level (cut out on a hill). Not saying that's your problem but it's worth checking. These trucks use high pressure engine oil to inject the diesel fuel. So if you don't have enough oil, you won't be injecting much fuel and it will run rough, maybe smoke and have no power at all.
Hope this helps.
Lou