I am having issues with loping and surging at lower rpm's, Maybe at higher but can't tell and someone said that I might be having a vacuum leak, 1986 2.8 V6. My vacuum is 15 at idle and drops when throttle opened then recovers slowly. I hear a small whistle sound when I let go of the throttle, need to get a better stethoscope, I can't pinpoint it yet, how do you check the throttle body- MPFI- for leaks and how do you rebuild them can they be?
My mileage is good but inconsistent as with the power or so I believe about the power. i am convinced now that my computer setup is ok and my sensors are doing what they are suppose to.

 

spray some wd-40 in random places with the motor idling. if the rpms surge while in one spot there is the issue.