3 minutes ago, Breezy_Pete said:

Surely that would generate a fault code?

Surely, yeah, but… electrical gremlins are tricksy little bar stewards as well you should know 😂😂

Does disconnecting the EGR plug generate fault code(s) and fault light? (asking @Erdmi )

This is interesting that there is no error code...

My ordeal started last year: an error code for the catalytic converter. I had it replaced. Then the jerking started. The engine fault light came on. Error code: fuel too rich. I quickly found this out by measuring the fuel pressure. It was 4.5 bar (my system is 3 bar). I replaced the fuel filter. It was still jerking... That's when I noticed the high IAT temperature. I pulled the EGR connector off for testing and the error went away. I bought a new EGR, and after VCDS training, the original jerking came back. The other parts were replaced before the EGR replacement (I described these in the first post). I'm at this point but I'm completely confused...

Maybe measure the 5V supply that goes to both the EGR valve potentiometer and the MAP/IAT sensor.

Red/green wire at each of those connectors, measure relative to the brown wire at MAP sensor, and relative to the brown/blue wire at EGR connector.

Ignition/contact on, or engine running when measuring.

I'll try to measure it this weekend.