That confirms what i said about LH keeping the idle speed high Rob, also you should change your Lambda sensor a bit more often
- the accepted lifespan is 100k miles or 10 years and pull fuse #1 to reset the ECU fuel trims after fitting to get the best results.
Note about the PAS - if the rack isn't in the central position when the steering wheel is in the straight ahead position, this will open one or other of the spool valves in the rack to provide assistance in the direction it thinks the rack is moving. This puts the pump under more pressure which creates heat in the fluid so it bols and creates ari pockets which lead to cavitation in the pump which puts more load on the pump drive and hence the engine. Once the fluid boils, it expands and will find its way out through the breather cap either on the pump if it's integral or later on the remote reservoir - the extra capacity of the remote reservoir versions gives a bit more fluid to be heated up before it gets to that point though.