Unless you can trail and error it yourself to try and pin point the problem you're gonna have to leave it in the hands of the mechanic.
But first off you're gonna need a scan tool to point you in the right direction to where to start looking first and then relate it to the mechanic if you aren't gonna proceed with it yourself

Lastly do you have the aluminium intake manifold or the plastic style one?

 

I took it to a mechanic but he couldnt tell what is causing the misfire, I live in Morocco where these engines aren't very common, it's rare to find an experienced mechanic in audi v8s. I did a scan and it tells me that all cylinders are misfiring. The manifold is aluminum, could it be related?

 

You godda invest some money in the ONLY true scan tool, see Ross-Tech: Home they ship world wide. These guys esentially cracked the VAG codes so these VCDS scanners are as good as the factory stuff. ONLY by scanning the car will you see the problems. Otherwise you will throw away a LOAD of money changing parts.

 

You godda invest some money in the ONLY true scan tool, see Ross-Tech: Home they ship world wide. These guys esentially cracked the VAG codes so these VCDS scanners are as good as the factory stuff. ONLY by scanning the car will you see the problems. Otherwise you will throw away a LOAD of money changing parts.

Hello!
Agreed, I will get my own scan tool soon, Thank you for the recommendation.
I did get a scan performed, it seeming like there is an issue with the intake manifold runner control selenoid stuck open that is the a fault that is directly related to the misfire, poor gas mileage and loss of power at low rpm.
Here is the scan results. The previous owner had a bad mechanic there is a bunch of missing connections:
But main faults are:
P0100

P0368

P2539

P2005


P2014

I did some research but any help with these codes is very welcome.

 

Look them up with Google I am sure you can find these...