Also, wouldn't it be considered poor tuning to leave the tc unlocked in 2, 3, and 4th gear?
not necessarily, it just depends on the
application.
a big single turbo truck with 400% nozzles (in a 'street' tune) would need the converter to be unlocked in 4th if it needed to be 'clean' while accelerating, even at hwy speeds, until the turbo comes on boost.
I mean...you could have the converter locked, but if you wanted to accelerate from 50/55mph to 70mph (say, entering the interstate on positive grade 'on ramp')...it would either not accelerate (PW cut waayyy back & no boost) very quickly...or it would likely be a smokey mess with the converter locked.
the e4OD tuning (I use) doesn't allow for PW modulation for the converter...but since the transmissions (E4OD & 4R100) and converters are identical (for all intents & purposes)...you could control an e4OD to have PWM duty cycle with a stand alone controller, or even perhaps existing tuning software that I don't use (for a regular TS style chip).