Engine hesitation and jerky

[G1en]

To the tuners and knowledgeable folk. 
 

After fitting new kinetex high flow cats and milltek y piece, the car has developed a very annoying lumpiness/hesitation when accelerating in certain gears/rpms. 
its like the ecu doesnt know what air/fuel mixture to use or throttle input is all wrong. It just kind of hangs for a second or two then feeds the power in. Not what i need for either general driving and certainly not on track when i get back to it. 
 

Link to video below, this was filmed on the driveway and throttle held steady in nuetral at only about 20%. You can see the revs drop slightly and hesitation just below 2k. My foot never moved on the pedal. Obviously this is magnified when im driving. 
 

Am i right in thinking this could be sorted with another re-map or could it be something else less/more expensive?
car has been mapped twice but last time to the old hfc’s which horsham had said prob degraded hence me fitting new ones, i havent had the ecu light come on since either, it came on every week previously due to O2 sensors. 
car also has tomei high lift cams fitted. 
i have already tried an ecu reset, throttle position reset, idle reset, and cleaned maf sensors just in case but to no avail. 
thinking outside the box could it be the crossover from closed loop to open loop map and a relatively big difference in afr’s which has been magnifield by the new cats?