stock converters are cheap and plentfull. put one back in and see what happens...

on a side note 2000 rpm brake stall on a TB stall with a radix is LOW! my N/A stock cammed 5.3 would get it up around 23-2400 and your 5.3 should have alot more torque.

have you ever thought about the problem being somewhere else? your current times look about identical to my 5.3 times with the TB stall but i was a stock cammed 5.3 without a charger. you should be mid/high 12's consistantly IMO. anyone near you have a wideband? im sure you have a boost guage and all that jazz too right?

what springs do you have in the motor? i had some valve float with the new motor that would make my truck feel and sound like the converter was locking and unlocking on me randomly at WOT.