P0300, P0301, P0302, P0303 and P0304
 

Hey!
I have an Audi A4 1.8T S-Line from 2006.

So I just had my CEL go on and it looks like it's P0300, P0301, P0302, P0303 and P0304.
I recently had the mechanic fix the following:
Air filter, cabin filter and one way valve near air filter. Also they replaced a CV axle and inner tie rod, but I cant see how that should have any effect what so ever.
Could this have anything to do with with the CEL popping up just two day after the fix. Or do I need to trust my mechanic more?
Is it fixed by changing the sparkplugs?

I'm hoping you can help me out just a tiny bit.

A quick update:

The car runs fine once on the highway.
It's only when idle that the engine shakes and the revolutions are a little jumpy.

Has anyone tried something similar?