I have never run my 90 down the 1/4......so I can't add anything from experience that I have, but consider that at WOT the engine vacuum is waaaay low...right?
The actuators require 8" hg to be fully opened and held fully opened, right?
If there is a leak at an actuator and/or both actuators leak, and/or a leak somewhere else in the 2* plumbing then would the actuators pull the 2* butterflys fully open and hold them open at WOT?
The reason for the pump,( if I'm not wrong...I wouldn't bet on that
) .....the pump supplies the vacuum to the 2* system that is not generated by the motor at WOT, right? I thought that the FSM said that at WOT there may not be enough motor vacuum to hold the 2* butterflys fully open, right?
I don't know except that it could be logical to suspect a performance difference at WOT between a Z with a good 2* vacuum system and a Z with a 2* vacuum system that is leaking, specially at WOT operation, JMHO.
Tom