Good day fellow members,

About 2 weeks ago, I was driving (in the city), and the car dies at a light. I try to crank the motor, cranks but wont fire. Waited 2min then boom it turns on. So I ignore, it no lights CEL light turned or flickered while this happened.
A Few days later the car completely dies, but this time on the freeway doing 65mph. No flashing cel and no hesitation, just completely dies. This time took it to a local Audi/Vw shop (UbTuning). Its been there for 10day. They test drove it it dies on them also. He replaced the o2 sensor (bank1) because he wasn't getting a reading, also vag-com the car and couldn't pull up any codes. First 2days he says it was the ecm, then said it was the o2, and last the harness. I wrench on my own cars, this was just a something I didn't have time to fix while on a busy work sched. Now I was doing my research online people saying its a issue with the CPS (cam position sensor) and crank sensor. While some are saying its a relay. I tell him to check those and he insist its a harness or ecm.

Problem: car keeps die but not everyday.
Question: What would cause this problem? And could it be a harness?

sorry for the long story. thanks in advance.