clean up or replace your temp sensors on the r/h side of the head (16V), 3 of them. and one on the back of the head also dizzy side is for the oil temp on the MFA. as for the 8v

are they on top of the oil filter

The MPG reads 99 on mine as well, ive checked for cracks in the small bore pipe under the bonnet that runs about by the bulkhead, it sems ok, but it does work breifly when its really cold

. i aint swappin the clocks for that thou, might cause more harm than good