After much stalling over the months, and headscratching I now know how to adjust the tickover speed on a V6 petrol.
Credit here goes to Fred at discount trucks, he worked it out.
There is an air screw on the rear drivers side of the engine at the top.
Metal body, with a small tube angled towards you.
With the engine warm and AC off use a flat blade screwdriver, turn anti-clockwise to increase the revs, and clockwise to reduce. Obviously don't turn too many times or the screw will fall out.
Rev the engine a few times, let it settle, then check with AC on etc.
