there is no screw really you just see the screw head
thats part of your problem . you are most likely lean and getting too much air
this site used to have pictures
http://www.supras.co.uk/resources/Mk...e.htm#Chapter3
the lexuz afm has a large bypass section allowing unmetered air you need to adjust that amount of unmetered air
it would have been good to install an air/fuel meter before so you'd have an idea where your mixture was at before
search google for "reg reimer afm screw "