Peter,
Are you suggesting that these problems may be unrelated, i.e. due to multiple items being broken simultaneously?

There is the
a) kickdown solenoid
b) upshift governor for controlling the upshift moment
c) the control rod - which connects to some other part of the system.

Is there nothing common which links these 3 things? If there is then maybe I should look at it first.

The car has not been sitting but has had regular use. Although I do not doubt the benefits which can be derived from fluid changes, I do suspect that these problems won't cure themselves through an oil/filter change.

Adam