1997 K2500 7.4L 4L80E No TCC

Heres my problem, no torque converter clutch being commanded on by the PCM. Using the Tech 2 scan tool I can command on the TCC and it works perfect. All inputs look ok, TPS, MAP, MAF, TFT, ECT, VSS, RPM and brake switch is not causing problem. I have monitored all these inputs with scan tool and scope. All looks OK. Catalytic converters have each been checked twice for excessive back pressure and test OK. Distrubutor bushings are ok, and are not causing faulty CMP readings. Cam Retard is 0 degrees. Reflashed PCM with newest transmission calibration and yet no change. Driving the truck, once its warmed up the PCM will command TCC on for about 5-10 secs and shut it off and will not attempt to turn it on again for several miles, then it tries again and does the same thing, turns it on for 5-10 secs and shuts it off again. Other than that it shifts perfect with no other complaints. After checking all this and everything looks ok I have no idea what to check next. Any and all suggestions or ideas would be greatly apprciaeted!!!