Before you go to the shop you should read this thread:
And if you have a lift pump like I describe on Post #3, then maybe you just have to tighten your 3-lift pump bolts. This is after you change your fuel filters if you have not already done so.
IMO, when diagnosing problems like this you have to separate the...
A) Electrical possibilities from the...
B) Fuel delivery issues.
And if you have a CAPS injection pump I highly recommend you upgrade to a FASS or AirDog electric fuel pump. (See diagram below.)
You made the right decision buying the diesel for lots of reasons that will become apparent over time. ...After you catch up on maintenance neglected by the previous owner. The V10 is a good engine, but the gas vs. diesel chassis are no comparison. And you diesel will hold it's value and give you many miles and years of pleasure (when you are not fixing it).
I hope this situation you an fix for free if you do your Forum research. You will need to access the top of your engine to get to the top of the lift pump to tighten your 3 lift pump bolts. And assuming this is your problem, you will be good to go, but I still recommend upgrading to a FASS to protect your CAPS Injection pump from early failure due to USLD fuel. ...And if you have a fuel delivery issue, installing a FASS is better money spent on this upgrade vs. spending your money on new fuel lines to the engine. I.e., if you have "flappers" in the fuel line causing a "foaming problem" the FASS pump should solve this problem, but in a different way.
For more help you should search my posts on www.IRV2.com
if you have and ISC engine. What engine do you have?
Call Cummins Care at 800-CUMMINS (800) 286-6467 with your engine serial number and they will tell you what type of engine you have and what type of injection system you have. Then tell us and maybe we can help?