I learned a lot from this web page about DISAs:
https://www.eeuroparts.com/blog/disa...s-replacement/ - I'm wondering what is causing my engine to lose power at high RPMs when it gets hot, concurrent with a rough idle at the lights - talking after at least 5 minutes of driving. I had a valve-lift motor problem causing the same issue before, which eventually caused it to not start. I will run an INPA check on it today.
@racebmwm3, glad you got the problem sorted out!