PCV System....Possible issue

Hi All.

Crap time of year to be having to mess with an unruly car but that seems to be the case!

I've just had an expensive MOT, part of which involved the EVAP Canister being replaced with a new breather.

Prior to the canister and breather being replaced the engine was all behaving fine other then an engine management light for the EVAP failure. Having driven the car home last night I am now getting rev issues, both at idle (where the revs are hanging and then jumping a little from the normal base idle) and  intermittently when coming up to junctions or to a standstill (when coming out of gear into neutral the revs stick at around 1500rpm, a blip of the throttle seems to cure it).

To me it seems like the PCV valve may be on it's way out but I'm not 100% sure. I have replaced the PCV valve once by myself but that was around 35k ago.

Is it likely that the PCV valve has gone again or in replacing the canister has the garage incorrectly attached a breather or similar and that may be causing the idling issues?

It is going back to the garage tomorrow but I thought I'd just see what wisdom Briskoda can pass on as usual.

Cheers