what a way to kill a lovely KL
You must have got her hot, they can warp the head, though they are all alloy, so it should all warp at the same rate. They have a stainless steel head gasket. How does it run? does it misfire? on 1 cylinder or does it just have no power and run really badly?
has it melted one of the PCV lines, they run a cone type air flow meter, and if there is any vaccumm leaks from the pcv/vris/anything then they wont run right. So check the pcv line that runs from the intake tube to the rear valve cover, the one that runs between the 2 valve covers and the one that runs to the pcv.
Has the intake tube deteriorated, they will cause them to not idle properly if they arent completly sealed.
Is it a manual?