Audi A6 C5 unstable IQ and rpm.

Hello everyone, i've got and interesting problem, my car is kind a rough when idiling, so i thought i'll check it with VCDS, i got only one fault of climate control. Then i've checked my IQ and it was all over the place, jumping from 3 to 6 or sometimes even 7. Then i've noticed that my rpm is too low, it was about 800, and it was also unstable, it was jumping from 800 to 840 up and down. Also my fuel economy was bad. I've changed my fuel filter, my injectors are good, i've checked them recently, so my only tought now that my injection pump might be bad, can i be right? How could i test it? what else can it be?
P.S I bought it with this condition.
My car:
Model: Audi A6 C5
Year: 1999
Engine: 1.9l diesel 81kw
Every advice is appreciated, thanks for spending your time on my post.
Have a nice day guys .

Well I've read that bouncing IQ is a sign of worn pump internals. You could bump the idle up a bit with VCDS adaptation. No idea what it's supposed to be. Mine likes 900, it's a manual.

I've already bumped my rpm's, it helped a bit, there's less shaking right now, VCDS stated that my rpms should be at 903. My lecture guessed that it might be the electrical part of my fuel pump, but i want to be sure before i start to take my car apart, maybe someone faced similar problem?

The pump may just be worn and in need of a rebuild.

On a related note: I'd give parts of my anatomy for a 4cyl TDI Audi A6. We never got those here. In fact, we never even got ANY 4 cyl in that platform, which is my personal favorite. We only got gas V6s and gas V8s, mostly automatic (like 99%) and mostly AWD.