96 P 4.0 holds back in 4th and 5th ?

[TVRSJW]

As title noticed that the chimaera on acceleration holds back and seems to miss fire on upper part of Rev range 4800rpm-6000rpm (linter is 6200rpm) bit only seems to do this is 3rd and 4th gear pulling away in first and then second car seems to pull cleanly the Rev limiter cuts in around 6 and a bit ,

so the missing is not the limiter feel ? It’s like the odd miss and holds the car back , I thought it was wind buffeting the car at first but have tested it where I can do 1st 2nd gear look all ok only 3rd and 4th (can’t go fast enough to test 5th lol.....)

Running super unleaded as always

Any ideas ? I’ve checked everything is connected correctly