help with 01 A6 2.7T starts but won't drive

[Myaudi34]

Auto 140k miles

Was driving one morning and noticed a significant loss in power / hesitant in acceleration (car didn't really want to go over 50mph) slowed down almost to a complete stop and the engine cut off. Would not start back up until about an hour later.

Currently starts up and idles (check engine light starts solid then begins flashing) once shifted into drive the engine cuts off and vehicle stalls.

Took it to 2 mechanics, first didn't know anything about these vehicles and said the engine is seized, next place said it's an internal issue with the engine.

I would appreciate any input.

[LINDW4LL]

First thing you need to do is scan the car for codes and post them here.