Car MK4 golf 1.6L engine code AVU 166000 KM

Hi all

I recently changed the PCV valve and MAF on the car as I was getting fault codes for them. All was good but today she was not running right and seemed a bit sluggish. I did a scan and I am getting the following codes when I scanned with VCDS LITE .

3 Faults Found:
16556 - Fuel Trim; Bank 1: System Too Rich
P0172 - 35-10 - - - Intermittent
16555 - Fuel Trim; Bank 1: System Too Lean
P0171 - 35-10 - - - Intermittent
16726 - Camshaft Position Sensor (G40): Signal too Low
P0342 - 35-10 - - - Intermittent

Any ideas what it could be. Maybe a faulty camshaft sensor or possibly the bank one injector. I am pretty sure there are no vacuum leaks but would have to check again.

Advice please

Many thanks

Zeroasylum