Settings A/F on EFI

The factory recommended settings have a fairly large safety margin built into them, in other words they are intentionally on the rich side.
Do you have a wideband O2 sensor that you can read the A/F ratio while driving? If not, tuning it is going to be difficult, and maybe a bit risky.
For on the highway, level ground, part throttle cruise, between 15.0 and 15.5 are going to work well. Idle mixture depends on a lot of things, so I can't give you a solid setting there, but generally it's between 12.8 and 13.5.
Wide open throttle is usually around 12.0 to 12.5.
Don't let the AFR stay any leaner than about 16.8 for any length of time.