Shouldn't the TC unlock when you take your foot off the accelerator pedal? While at a steady speed above 48 mph and TC locked, when I let the engine go to idle (or try to) my TC is staying locked unless I tap on the brakes fairly hard. I do have a modified VB and 3disc converter but I don't think that should matter, right?

9 hours ago, rotohead said:

Shouldn't the TC unlock when you take your foot off the accelerator pedal?

The torque convertor should unlock and the RPM drop.  The TC lock up switch is put in to keep the convertor locked.        I believe the APPs going to idle circuit sends a signal to unlock the TC. 

Should definitely be unlocking. Do you have any sort of external lock up switch? If not, I’d be talking to your trans builder and asking questions.

Could go ahead and ask our site transmission builder. @Dynamic is a good transmission man and might be able to help out.