Na, I'm pretty sure it isn't the secondaries. It happens after they open up. I can feel them at about 3700 rpm. This happens after that. So far, no problems with a full tank, but with less than 1/4 tank, it is repeatable.
As I am having the same problem, only for me it will occur not only in first but also second....as long as the revs are high enough....I was also about 1/4 of a tank tonight so I will try filling tommorow and see if the problem persists....I still have to take the car in for a tire rotation and rebalance.....sucks
2000 Black Contour SVT
Western/Central Massachusetts
same with me, under a quarter of a tank I get pissed off as I try to accel and end up buckin like a freakin porn star, wtf, it sucks, new fuel pump here i come