I have a 91z28 350 tpi. it does not want to change gears at wot it pulls the motor down unless you let off the gas. this happens at aprox.4300 rpms. Ihave the B&M wot upshift kit but it was stalling before it was installed. Could this mean a bad transmission or torque converter?? the tv cable was adjusted to factory and many other settings it does not seem to be the problem. Thanks for any help