* How are you controlling the vacuum level the engine encounters? - I have a guage inside that I use to observe the vacuum. I am not sure that I answered your question though. * Are you loading the engine with the brakes or up a long hill? - No. Just a slow steady increase of speed from a stop but not enough for the 3-2 downshift to occur.
Typically the vacuum level with increase as the car picks up speed (and the load is reduced). If you are attempting to maintain a constant vacuum level, I assume you are continuing to increase the throttle opening when the vehicle picks up speed. This makes me more suspicious that the secondaries may be opening during your test. Another way to increase the load on the engine is to do the test on a long uphill, or by applying the brakes while applying throttle.
Given the duration of lean period, and on the assumption that the secondaries are beginning to open, it seems the problem may be more than just the secondary AP. What are the current values of IAB and IFR on the secondary side? You may need to ponder the transition circuit behavior on the secondaries.
