Sorry for hijacking - this could help u if its not TCS related -
I had that infamous flat spot between 4700-5400 rpms, the car would also hesitate for a sec in fifth gear around 3rps when booting it, although my TCS doesnt work at all - no light on dash at all.
Changed to 0.8mm gapped NGK copper plugs, left my standard coils in. No change to above problem.
Then yesterday after reading a few bits on SAU, I reset my ECU - take off the battery terminals, stab the brake pedal a few times (brake light on/off) to drain off all the charge, then re-connect and go for a drive.
I'm just amazed to say after the ECU reset - the flatspot is almost completely GONE, not only that, the car feels so fresh, crisp and very quick to rev and GO!!