2011 Picasso 1.6hdi misfire/stumble

Hi all ive joined up in the hope you can help with an issue on my partners 2011 c3 Picasso 1.6hdi (90), basically she complained about a misfire lack of power on cold days, seemed ok at first until you get a few miles on it and give it some load when it stumbles/struggles, once its done it a few times (or maybe just got fully upto temp?) it seems ok and i struggled to get it to repeat the issue, i have been able to get it to repeat but hard to pinpoint as intermittent.

Anyhows i plugged in my OBC unit and Torque app scanning for erros and looking at data, inlet temp looked miles off and also had code for it so we replaced the Maf/temp sensor unit, all we could get on the day was a cheap Starline branded one from ECP, im always wary of these cheap sensors especially from ECP! but we had no choice that day, anyhows car seemed better and no more error codes with new sensor. I also removed and cleaned EGR valve but it wasnt too bad, replaced fuel filter and basic check over nothing obvious otherwise

Move on a few weeks she tells me its still doing the stumble issue on colder mornings, at first it seemed to just be very cold sub zero days but im now told it does it even when 3-5c outside.

Im going to scan it again this weekend but not had any codes or light on dash last few weeks so not confident it will show anything up, hopefully it gives us something to go on though!, im using the Torque App and OBD adaptor to scan but if anyone can recommend a better App for the citroen as i know some are better than others let me know please

She wants to replace the Maf/temp sensor with a genuine one ( i scared her about the cheaper ones) which im tempted to do but its a expense that im not sure will fix it.

Any ideas welcome on things to check

Thanks
Ian