Very hard vibration when in D/R gear idle standing 2.7TDI Multitronic

[fecovas]

Hey everyone,

I have A4 B7 2.7TDI 178ps FWD Multitronic. For the past 5 months I have been dealing with an occasional very hard/heavy vibration when standing still on idle, but only in either D/R gear if I shift to N the whole vibration thing is gone as well as when you start moving the hard vibration/shaking is totally gone and car drives normal. The issue is not present when the car is cold and keeping the RPM around 1k, as soon as it dips lover and starts warming up, there is a high chance, that when stopped at a red light and waiting stopped in D gear, a very heavy vibration or even shaking is felt through the whole car and it's not some slight vibration, that is barely felt, it's a really hard vibration, it almost feels like the car does not know, that I'm stopped and holding the brake pedal, so it keeps the engine loaded up (like it's supposed to be driving). Multiple service workers have looked at it, ran multiple diagnostics and were unable to find anything wrong. Transmission sucessfully passed adaptation tests, injectors were all fine according to VAG-COM. The car has DPF and catalytic converters cut out, EGR is disabled as well. Both engine mounts were replaced with new OEM ones.

The main issue is this does not happen 100% of the time, it's seems to be a 50/50 chance to either have it or not, but as soon as the engine is at least a little bit warmed up, that chance raises significantly. The funny thing is that whenever I would bring t he car in for inspection, the vibration/shaking would not happen and the car would just run like normal, so it's really frustrating as it does happen 100% of the time.

I'm honestly just lost and don't know where to look at, could this be some sensor/electric part of something, which causes for the car not to understand, that the brake pedal is pressed with car stopped and that the engine should not be on a load? Because that would make sense for this to happen.

Any advice would be appreciated.