Strange rpm increase/throttle when braking - A6 2004 1.9TDI Multitronic

[molcos]

Hello.

For some time now i have had this issue with the car increasing the rpm and not wanting to stop when using the brake.
This happens when the engine is cold, usually first 10 minutes in the morning when driving the car.
Its almost like driving a manual and not using the clutch when coming to a stop, almost like the engine will stall and stop.
When the car finally stop it is usually accompanied with a very jerky acceleration, almost like a gearshift without the help of a clutch (not that dramatic though)

The idle RPM is also somewhat uneven, it can in some cases go up to above 1200rpm and stay there, but it usually sits under the 1000rpm mark.
I can see the needle moving slightly up and down, i remember from a year or so that it was stable.

I can mention that i have shifted all the filters and completed a oil change 3 days ago, just to rule out any airflow problems.
I heard from a technician that it could be problem with the EGR valve, so after some reading online i have bought a EGR delete kit from Darkside development.
It should arrive in a few days.

Today i checked a bit more online and noticed this article about brakes.
I cut and pasted the interesting part.

*Cut from wikipedia*
Most modern vehicles use a vacuum assisted brake system that greatly increases the force applied to the vehicle's brakes by its operator.^[1] This additional force is supplied by the manifold vacuum generated by air flow being obstructed by the throttle on a running engine. This force is greatly reduced when the engine is running at fully open throttle, as the difference between ambient air pressure and manifold (absolute) air pressure is reduced, and therefore available vacuum is diminished. However, brakes are rarely applied at full throttle; the driver takes the right foot off the gas pedal and moves it to the brake pedal - unless left-foot braking is used.

Because of low vacuum at high RPM, reports of unintended acceleration are often accompanied by complaints of failed or weakened brakes, as the high-revving engine, having an open throttle, is unable to provide enough vacuum to power the brake booster. This problem is exacerbated in vehicles equipped with automatic transmissions as the vehicle will automatically downshift upon application of the brakes, thereby increasing the torque delivered to the driven-wheels in contact with the road surface.
*End of wiki*

Could this be the issue with my car, Not being able to provide enough vacuum to the brake booster?
It says the problem is more prone for automatic transmission cars, like mine.

I think problems with the gearbox should be ruled out, i had problems with it for a few months back and replaced the whole hydraulic part thingy at the back of it.
Changed all the oil at the same time, previous to that i changed a chip on the motherboard that made the transmission go into limp mode all the time.

I have checked the car with a VAG tool and there were no fault codes at that time, but right now the yellow engine warning light is lit.
It is usually lit, but the day when we tested the car it was of, so i might call the dude and make a new test now that the car has the warning active.

Please, any help in this matter would be of great help.
If i have missed any important information, just ask and i will fill in the blanks.

Regards

[Peter D]

You have a TDI so no throttle vacuum. The vacuum is provided by the tandem injector pump so you need to check all the vacuum hoses for leaks as this could be your problem. Regards Peter

[molcos]

You have a TDI so no throttle vacuum. The vacuum is provided by the tandem injector pump so you need to check all the vacuum hoses for leaks as this could be your problem. Regards Peter

Thanks for the reply.

When you say vacuum hoses, is it related to the EGR valve or some other system?
Sorry but im just a noob when it comes to cars and problems.

Give me a computer and i will be able to fix most issues though

[molcos]

Just to add to the original post.

I drove the car today and the extra throttle was actually very constant at around 1200rpm when driving home.
It would have been normal if i had applied a little pressure on the pedal but my foot was completely of it.

When i brake the engine wants to keep the same rpm and not wanting to stop until extra brake pressure is applied.

What is the best way to find a vacuum leak? i have watched videos with different methods.
Water and soap to look for bubbles, WD40 spray to watch out for idle rpm changes.

Or just take it to a repair shop and pay a lot of $$$ for troubleshooting the car.