Need some 7.3 / 4r100 help

I've got a 2001 f250 with my motor out of my old 94 in it running 238/100 and an s269. Has a built 4r100 from diesel site. Trying to get the thing ready for diesel drag race and show this weekend and last night it started acting up. When I try to build boost by power braking like you would off the line it bogs down, blows ton of black smoke, won't build any boost, or rap above 1200 rpm. Driving normal it shifts through all the gears and locks tc as well as pushes 50 lbs of boost. I've checked to make sure it's in 1st gear and the tc isn't locking up while I'm trying to power brake it with my auto enginuity. I've checked the turbo and all related exhaust and charge air lines/cooler can't find anything wrong. And driving normal it's making 45-50 lbs just like normal so I think the turbo is fine. I was thinking tranny but it isn't locking the converter or shifting to say 4th gear. That's what it feels like like it's bogging down. Anybody got any input it would be greatly appreciated. I really wanna get it going tomorrow this is the one big diesel only event in my area thanks

sounds like the converter is too tight. What tunes are you running? have you discussed the issue with your tuner?

I just got off the phone with gearhead they tuned it he said since it was running normal and stopped prolly wasn't on the tuning side. They all thought most likely the tc. Matt at irate said he was 99 percent sure it was sprag in the tc broke cause of what I described to him and he said it will make a wierd chirping sound which is exactly what mine did before it stopped building boost. Bob didn't think that was the case because i watched torque converter slip with my ae and when I power brake it the computer shows it's slipping to lil over 1000 rpm which is just about where the engine stops at. Gonna try pulling the hydra out of the pcm other than that I'm lost. Could also swap a stock converter I have from another tranny in just for this weekend idk.

I'm at a loss on this one..... it's literally the first automatic I've owned. I'm leaning towards torque converter but I really don't know. Thinking about swapping the stock tc I have sitting in the shop in to see if that's the problem and get me racing this weekend. Just affraid of ruining my new tranny if it kills the stock converter