Hello I would like to help you with this
I will be looking at your problem so maybe a few minutes before and get back to you.
One possibility that could be causing this would be improper fuel pressure or delivery.
I would suggest testing the fuel pressure to make sure is it within the proper range at all RPMS. There may be enough fuel pressure to start the motor but not enough delivery the required volume to maintain the engine RPMS above 2000. Below are the specifications for the fuel pressure. Please check that and let me know
I hope this helps you,
Please let me know if I can help further, and please remember to indicate that I have helped you today by pressing the accept button.
the turbo should not restrict the rpm in neutral.
you could have clogged injector though. I truly believe this is a fuel delivery issue.