Toyota Repair: 92 previa runs like wrong firing order after 2000 rpm., fuel pressure regulator, spark plug wires

Question
Hi Ted,you did help me before with this vehicle.It did not start at all.You said to check fuel pressure.Since then the fuel pressure regulator was changed and to my astonishment,it started on the button.But rev it over 2000rpm and it seems to miss quite badly.There is a brass screw on top of the throttle body which when turned either direction,changes the revs.This was originally screwed right in,but if i unscrew it a bit it runs slightly better but the revs increase.The manual has nothing on the throttle body,so i am a little lost.kind regards martin.
P.s thanks for getting it to start though.

Answer
Possibly an engine misfire caused by a cracked distributor cap or burned rotor, bad spark plug wires or spark plugs, check the spark plug connectors they can leak and short to ground. The adjustment screw is normally covered with a plug, sometimes mechanics drill the plug out and remove so the idle can be adjusted, normally the idle is set by the computer and if everything is working normally the idle doesn't need to be manually adjusted.