2008 volvo d12 dies intermittently and at random

Hello all, I have a old volvo d12 with 1.1 million miles. The truck runs great, idles great, overall a great truck. Recently the truck started shutting down at random. The speedometer will go to 0 then bounce back, loss of power, and the trailer abs will flash with it. The vecu fault is MID 144 PSID 230 FMI 4. And I have various tcs faults as well. Its worth noting that my oil pressure sensor is faulty as well, but its been like that since I bought the truck.

I took it to a mechanic, they said the alternator was bad, and had shorted. I was skeptical but had them replace alternator and repair the harness today. 1500 dollars later, im on a load and the problem is still here. I don't mind fixing the truck properly, I just dont want to throw parts at it hoping to find the issue without proper diagnosis.

Any advice?

 

Lol the truck stopped running on the side of the road. The ground from the starter to the block broke internally. To avoid a tow...I used a stainless steel hose clamp to put it back together. Fixed all my problems....after weeks of searching lol.