I replaced my balding tires on my 1998 BMW Z3 recently. When I accelerate to high RPMs (4000+) in third gear going uphill, the ASC kicks in and reduces power. If I shift up to fourth gear, the ASC stops draining power and its light goes out.
Does the ASC generate fault codes that could be used to diagnose the problem?
Maybe someone could drive along side of you and see if the rear tires really are spinning.
You may be having intermittent wiring connector contact problems with a wheel speed sensor. It could be corrosion or yes, something may have been jarred loose during a wheel change. There should be stored fault codes.