Craig --

One important aspect of adjusting the throttle on the early electronic FI systems is to be sure the throttle switch does not act as the mechanical stop. So you need to adjust the throttle (mechanical) idle position with a set screw, then adjust (rotate) the throttle switch so there is still a bit of rotational freedom.

As I recall (and it has been a while since I looked under the hood of my ES's -- like 15 years), the switch has a series of "zig-zags" that a wiper slides across as you open throttle. The computer counts the "make-breaks", and infers throttle position. There's also a contact closure that tells the computer when you've returned to idle position.

It's important that the switch not be the mechanical stop AND that the idle contacts still close. It's a delicate adjustment.

A good way to clean the "zig-zag" printed circuit in the throttle switch is with a pencil eraser.