Could someone please help, just been out for a spin in my 93 Escos and for some reason when she reaches the top end of boost the turbo seems to cut out and then back in again

This has never happened before, but I have recently fitted a group A K&N filter to the car,when taking out the old air box I noticed a small air hose at the base of the box which attaches to the actuator, This now has nowhere to go, I was told that this vents to atmosphere and does not need to be attached, could this be my problem?

A bit worried, can someone please help as I want to drive the car to National Day tomorrow