I managed to eliminate the transmission as the problem and thought the VVT Solenoids could be the culprit where the transmission would change down because they weren't advancing the valve timing quick enough when more power was wanted.
After reading this...
3. Engine stumbles when climbing hills or under load
A faulty VVT switch will also cause the engine to misfire or appear to stumble when your vehicle is loaded with extra weight, climbing hills, or when you apply quick pressure to the throttle for instant acceleration. This is caused commonly by an electrical issue with the switch and not always the switch itself. If you notice this problem and contact a local ASE certified mechanic to inspect the issue, it's highly likely that they won't have to replace the variable valve timing switch. However, proper diagnosis is needed to verify that it's a problem elsewhere. If you ignore the problem, the potential of further engine damage will increase.
which exactly describes the issue i have. I decided to take it to the local mechanic and get them to remove the solenoids and give them a good clean as well as checking the electrical side of it was working properly. I knew there was only one bolt holding each in and it ended up 1 hour labour all up to do the job.
The solenoids weren't that bad but they gave them a good clean and the result is i think it's finally running properly. The VVT seems to advance as soon as i put my foot down just a little instead of hesitating and causing the transmission to change down and the engine to rev. First time i put my foot down i just went wow..!! big difference but because of lockdown i couldn't take it for a long drive but will tomorrow now it's lifted.
Two transmission shops and 3 different mechanics couldn't work it out but lots of internet research and finally the quote above made me confident i knew what it was. Seems a very small bit of crap in a/the solenoid/s may have been causing the problem.
