I have said it before and I will say it again.... An Internet forum is a bloody nightmare for diagnosing these sort of things..... . However in a bid to help, I will throw in my 2p worth.

Have you tried the road speed sensor? It sounds like an intermittant fault.
Have you tried cleaning the iscv with carb cleaner?
Have you tried cleaning inside the throttle body with carb cleaner?
Does it sound like there are any air leaks anywhere?

Finally..... You might receive more replies in the tech q and a area as the Xr room is a bit dead of late.....

Good luck mate