Cummins ISX problem need help

Was wondering if anyone can help me out with figuring out what’s wrong. I have a 2005 Peterbilt 387 with an ISX. So I was in idle for a couple hours & all of a sudden the motor started to lose power & it shut down, I then tried to crank it up 2-3 times after it started up again , but like if it was going to turn off , & it did. Tried cranking again & nothing after that . Tried 3-4 more times & still , it cranked , but no start . I left it alone for an hour & a half & still, crank but no start. So I gave it a shot of either & it started right up & was running & did a short 50mile load but then the truck out of nowhere, it started jerking while driving. Someone suggested it was the transfer fuel pump. Anyone that’s gone through this, I’d appreciate yalls input . Thank you!

 

Did you have to replace the complete assembly? The transfer pump, gear pump & the base ?

 

In my case I don’t think it’s the gear pump. Cause it wouldn’t have started back up or been running if that one was out. Hopefully it’s just the transfer pump.