Hi Again All. Throwing out the challenge again.

Lets start with the simple stuff.
I have a UK Audi A4(190 6speed Manual) 1.8t B6 year 2004 BEX engine.
I had the engine light come on with the code for lean bank 1. The only code that has come up on my laptop reader.
I consider my self good at fault finding, but this is starting to wind me up.
Part 1:
So i went through the following to iron out that fault.
1. Oil (Audi equiv) & Filter change.
2: New Bosch super4 spark plugs x4.
3: New set of Coil Packs x 4.
4: Replaced the PCV Valvle & attached 3 way hose for good messure.
5: Ran tank dry and filled up and used Redex fuel systemcleaner.
6: Cleaned Air mass housing and grill. Replaced Air flow Mass meter. (OEM Equiv)
Cleared the code yet still runs miss firing and top end speed very poor.
Using alot of fuel due to running rough too.
So i replace the spark plugswith Bosch again.
Checked they all were firing, which they were.
All coils firing and in firmly.
Put old air flow meterback in & it ran very rough, so knew the new one
was ok. So put back in. Reset all codes & went off again.
It still is very rough yet no engine light yet.
Part2:

Right i thought i solved it.
I found & replaced the faulty split Vac 3way hose and the broken vbreather alve inside.
Then replaced the down Vac pipe to the engine block. Which was amazingly tricky to remove.
As like everyone says, it breaks off in pieces. Replaced with clip & rubber seal ring.

2.5hrs later all nice new pipes fixed in & re-clipped in.
Reset engine management code.
Engine hissing is considerable less. I thought....yes.........I get all that smooth turbo power back that
i had before!!!!

But now driving is still terrible, the loss of power is quite significant.
Top end speed is massivly less & struggles to accelerate on the hills.

Before all this & the engine light coming on, the cars performance was awesome.
But after finding the split vac hose, replacing 2x faulty breather valve, replacing all coil packs, 2 lots of bosch super4 spark
plugs tried, oil & filter change. Im pulling my hair out.
It isnt jumping or jerking as it did, just real loss of power or even turbo boost.

Questions & support please all.
1: Could it be faulty coil pack leads, yet no engine management light yet. But sparks are clearly working.
2: How can i check if its the turbo, would that come up on engine fault light.
3: What are my other options to check & iron out please.
4: The Cambelt was done a while back but with the new coils, sparks & hoses could it be timing??
Help please gang
Thanks
Danny