Bogging down at 8k rpm

[Sannox]

Hi all, been a while since I was last on, looked through the threads and can't see anything on this. My 2002 will red line no problem in 1st, 2nd and 3rd but 4th upwards, get to 8ooorpm and it bogs down, all power gone, won't rev past unless I pull in the clutch, roll off the throttle and all good. It's across all four cylinders. Any thoughts?

I still have problems with it sometimes, not always, cutting out under acceleration, sudden and brief, bit of a problem when overtaking, wondering if this is linked to the above issue or not.