Try replacing the filter.

As the reverse clutches go they can fill a filter in just a few miles. You problem is classic symptom of a packed filter.

If that don't work I would loosen and retorque the valve body. Internal leakage can cause such temp dependant problems.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician