Is it possible the lockout is caused by the lockout solenoid, the same out that initiates the skip shift. I posted something a while ago about downshifts from 5th to 4th while rev matching causing a lockout of 4th. I tried a few times to force it because I was pissed the car was locking me out and could get it in. Sad thing is I could easily rev math downshift in my old 93 celica. It was like I was trying to downshift at 7k+, more like 5k and it would try to lock me out. Sadly I will begin saving up for a T56 Magnum so that I know I have a trans that isn't rated exactly at the torque the motor puts out and so I know I have a trans that doesn't use that cheap, stupid, remote shifter bracket damn penny pinching Hermans.