I wonder if i could try and do a no lift shift pull to see if that would verify your theory, but i have swapped ecus from a rebuilt factory ecu- to a chrome ecu. I would imagine that is where a ‘no lift shift’ thing would be stored.My old brain just kicked in and I think I might be able to help you.
My son was having a similar issue on his 93 VR4 and it turned out to be something that he had no clue about.
He was having issues at around 5000 rpm and it turned out when he flashed his last tune, somehow NO LIFT TO SHIFT got turned on????
It was set to trigger at, you guessed it, 5000 rpm....
He turned it off has been good ever since.
Hope that fixes your issue....
Clutch not pushed in, i drove it today and tried out everyones theories. Im going to post a response after this to go a bit more in depth.Here is the relevant post about no-lift-to-shift: Chromedecu.org | No Lift to Shift (NLTS)
In your original post it said the car will rev to redline in neutral no problem which I don't think would indicate NLTS was activated. Chrome needs a signal from the clutch switch to get NLTS to work. The only way I could see it would be if it was set up "backwards"(if that's even possible) and OP meant "neutral" he was talking about with the clutch pushed in.