Intermittent shift problem S4 Shape V6

[Renier Meyer <r.meyer@mweb.co.za>]

We are having problems with the shifting of the V6 2.8l  S4 shape
Audi. The type number is listed as 4A2E.
It has an automatic 4 speed box with sport selection knob.
The box does not shift into fourth every now and then.

The symptoms are:
Shifting OK when when cold.
After a while the box does not want to shift to fourth. All other
gears shift OK

The agents checked the system with the programmer and it shows :
Intermittent Fault,
When the faults are cleared, the system works Ok for a while, but
later starts doing it again.

Any ideas, or things we can look for? According to the agents the
box is controlled by an computer system? Is it wiring, hydraulics,
or the electronic controller that we should look at.

Any help will be appreciated.
Thanks in advance.

Renier Meyer
r.meyer@mweb.co.za