High RPM idle and steering wheel shaking

[Touran]

I have a 2008 Touran with a 2.0 TDI 170hp engine.

2 weeks ago the RPM on idle started staying at 1100 from the usual 800-850.This happened everyday, but not every time the car was stopped.

I did a check and not a single sensor or code was showing on the computer.

In the meantime I changed a cracked water pipe which made the car loose about 1 liter of coolant (replaced now).

And also when the RPM is at 1100 and when I press the brakes the steering wheel tends to shake or block for a fraction of a second when turning fast. Tried turning the wheel with normal RPM(800) and the steering wheel is absolutely fine.

The car has been checked by many mechanics, but none have solved my problem.

Anyone who has had the same problem or can give me a solution? Thanks in advance.