OK, I just cleaned out the throttle body/MAF on my Tahoe and the improvement was so dramatic I thought I'd use the rest of the cans of cleaners on the '05 S80.
Alas, I can not seem to find the throttle body - at least it is not where the one pictured in the tutorial over at Matthews is. Am I going to have to remove the intake manifold and whatever is over that just to get to it? Seems like there must be an easier way.

 

ya actually i have been wanted to clean that too on my 2006 2.5T too.
This is what i found :

-Remove the intake manifold between the front cover plate and the air cleaner (ACL) housing.
Disconnect the battery negative lead.
-Disconnect the hose between the charge air cooler (CAC) and the throttle body (TB) at the end of the throttle body (TB). Move to one side.
Remove the tie strap at the connector.
-Disconnect the throttle body (TB) connector.
Remove the throttle body (TB).
Clean the mating surfaces thoroughly.

Install

-a new throttle body (TB) with a new gasket . Tighten to 10 Nm
-Connect the throttle body (TB) connector

the tie strap at the connector the pipe between the throttle body (TB) and the charge air cooler (CAC)
the intake manifold between the front cover plate and the air cleaner (ACL) housing
the battery negative lead. Battery, disconnecting

Now i dont think you have to remove the body i.e. i guess you can clean while the body is bolted because if you then install it "After replacing the throttle unit, the throttle unit must be adapted using the vehicle communication input: Adaptation of the electronic throttle unit. Remedy as necessary". hmm