Engine judders/surging at 3k rpm

[CALLUMSAMUELS]

As title says, it is a 3plug vtr with a supersprint 4-2-1 and standard exhaust, i originally had an icv problem and so i changed it for a spare i had and it cured the idle, but that was when this juddering started.
i have changed map sensor, crank position sensor, coil pack.
i have clean the injectors and everything looks decent there.
i wondering whether it has anything to do with my second lambda sensor, as it is currently cable tied underneath the headlight to get clean air, if it got damaged could that be causing it?
why does it feel normal to drive up until 3k i dont get it?

[Nimix]

I'm listening here.
My single plug gti is doing the same, changed the map sensor and temp sensor, a tester reviled that the lambda was faulty and running 30-650mv not 200-800 so unplugged it but the symptoms are still the same.
Juddering and coughing at 2500-3000rpm and clearly down on power.
Flooring it removes it, while maintaining steady gas prolongs the issue

[CALLUMSAMUELS]

what tester did you use to test the lambda sensor?

[stevo67]

Have you got the 2nd lambda sleeved?

[Nimix]

I work at Peugeot, so used thats one

[CALLUMSAMUELS]

no i dont think its in a sleeve.

[CALLUMSAMUELS]

put the obd machine in came up with knock sensor, cleared the code and now shes running a treat.