TC not locking at WOT

[V6POWER]

Rebuilt the trans and it runs great during normal cruise and shifts where it should and tc locks correctly. Problem is the tc is not locking at WOT. I get 28% slippage at 98 mph and the rpm's do not drop at all. I am using the 700 solenoid and I removed the check ball in the turbine shaft, even though I have lock-up tc. I did this because Steve at Pat's said 50% of his lock-up customers remove the check ball to help remove the trans fluid quicker for lock-up. Any suggestions to correct this non-lock up at WOT problem?