Troubleshooting help for 4kq

[CTDiesel at aol.com]

Can anyone suggest as to why i cant get the duty cycle on the ISV below 60%?
There are NO vacuum leaks and as i turn the screw on the side of the throttle
body the lowest i can get is 60% in a certain place everywhere else is 100%.

The Bentley doesnt help much on the subject and neither does the Bosch Fuel
Injection, Probst book.

Help me if you can please!
DJ