When I first took my car out (after new trans, shift kit, and 2800 stall) it felt sluggish and would shift at like 4500 RPM at full throttle. I messed with the kickdown cable and got it to shift at like 6100 and it would shift very hard at part throttle. A bit more messing and it now shifts right at redline (5800). The only thing is that at full throttle when it's going through third gear, right around 90 mph the rpms drop about 300-400. It always happens and always at the same point. RPM's are around 4500-4700 and drop to 4200-4400. Is this TC lockup and will it stop if I unplug my transmission when I race?

 

No one?