try relocating the oil take off for the turbo. on the 4x4 it comes out of the side of the head which means it takes some pressure away from the head. try blanking this & using the 2wd setup where the turbo takes its supply from the oil pressure swith take off. to do this you will need 2wd turbo oil feed pipe, adaptor union & either a different oil filter (escort 1.8 zetec filter fits nicely on mine ) or mess about moving the position of the ally oil takeoff the oil filter screws to to provide clearance for the oil feed union. also a suitable bolt to blank off the oil feed on the head