I think if I was lean, the car would act differently. It is just like the supercharger is disengaging at around 5000 rpm. I unhooked the battery cables. I notice the LTFT went back to zero after reset. They were hovering around -7 after about 20 miles. I guess this would indicate that fueling is okay. I don't have a wide band, just the simple ultragauge.

If I real gradually raise the rpms I can get it pull past 5000 before it falls flat.

Have you ever heard of a supercharger clutch being weak and not holding at high rpm.

Sure does seem like something is telling the supercharger clutch to disengage.

If the belt was slipping, I wouldn't think it would fall so flat so fast at the same rpm.