just put 4.2 v6 in 1998 f150 on the back of the lower intake there is two controls on the lower intake for the butterfly inside the intake . I have no vacum at these two switches
The vacuum controls are used to bring additional air into the engine at higher engine speeds. You would have to test at the correct time to detect vacuum. Tie a piece of string to the movable part of the vacuum control. Tape the other end down, with the string having no slack in it. Now go run the truck up to 60 MPH at wide open throttle. Examine the taped down ends. If they have been pulled away from the tape, the vacuum controls are working correctly. If not, follow the vacuum diagram from the 4.2 engine. If that is correct, you will need to follow the wiring from the 4.2. I do not think the 98 had all of the wiring for the later engine. This may get complex. If need be, you could get a RPM switch from MSD, or Accell, and use it to trigger the vacuum controls at whatever RPM you want. Good luck.
Vacuum Control
Re: Vacuum Control
