For the steering wheel, when was the tracking last done?
http://www.volvoclub.org.uk/dc/dcboard.php?az=show_topic&forum=14&topic_id=10843&mode=full&page=4
for a similar problem.

If the revs are always limited, then maybe the limp home mode on the ecu is activating. If the revs are only sometimes limited after shifting, then maybe you have a vacuum leak that opens up only when you change gear (and the engine rocks a little especially if the engine mounts are worn). Or maybe the fuel mix is way off for some reason. Perhaps even your cat has collapsed and is blocking the exhaust flow.

As for the engine temp, I'd check the thermostat actually does open...I've used a boiling kettle for this in the past.
Perhaps it is boiling over because your cylinder head gasket has gone?...is the oil the right colour or is there lots of brown cream, especially on the filler cap?...lots of possibilities, so what have you checked so far?