2002 GT Engine Sputtering Under Load ONLY, Vacuum advance problems?

Hey guys, I’ve been a regular at reading the threads here for a few years but have never made an account before. I think I have “hit the wall” with my project car. Here are my mods:
78mm BBK throttle body
SCT iTSX Bluetooth tuner
K&N CAI


The motor in my car is rebuilt from Fraser Engines in Michigan. I did a motor swap and had my brother in law install the motor because I did not have any time to do so. The original motor in the car was stuck to the transmission so he had to pull them both at the same time. When he put my driveshaft back in the car he did not seat the C clips right away and tore apart the tail shaft housing and it almost came through the floor on me. My transmission was completely wrecked and I needed to put a new one in.

I found a 4r70w and a driveshaft from a reputable junkyard near me. the transmission came out of a Ford Explorer. I completed the swap but I’m having a really large problem.

In park or neutral, my car runs great. Any time I put a load on it it sputters when I hit the throttle.

I unplugged each coil pack and found none of them to be faulty, I have pulled each injector and found the same. I disconnected the MAF while running and that made the engine die. I disconnected the IAC and it died also. I made sure my PCV system is not clogged. I unplugged the EGR while running and it only made it worse. I finally hit the wall and I was talking to my friend the only thing I couldn’t rule out was my cats being clogged. I unplugged each O2 sensor and I thought it sounded a little better so I cut my upstream cats to try and see if the sputtering/stalling would go away and it didn’t help at all!

I know multiple brains are better than 2 so please let me know any test processes/where to look next. I am truly stumped. thank you in advance!
 
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Hey guys, I’ve been a regular at reading the threads here for a few years but have never made an account before. I think I have “hit the wall” with my project car. Here are my mods:
78mm BBK throttle body
SCT iTSX Bluetooth tuner
K&N CAI


The motor in my car is rebuilt from Fraser Engines in Michigan. I did a motor swap and had my brother in law install the motor because I did not have any time to do so. The original motor in the car was stuck to the transmission so he had to pull them both at the same time. When he put my driveshaft back in the car he did not seat the C clips right away and tore apart the tail shaft housing and it almost came through the floor on me. My transmission was completely wrecked and I needed to put a new one in.

I found a 4r70w and a driveshaft from a reputable junkyard near me. the transmission came out of a Ford Explorer. I completed the swap but I’m having a really large problem.

In park or neutral, my car runs great. Any time I put a load on it it sputters when I hit the throttle.

I unplugged each coil pack and found none of them to be faulty, I have pulled each injector and found the same. I disconnected the MAF while running and that made the engine die. I disconnected the IAC and it died also. I made sure my PCV system is not clogged. I unplugged the EGR while running and it only made it worse. I finally hit the wall and I was talking to my friend the only thing I couldn’t rule out was my cats being clogged. I unplugged each O2 sensor and I thought it sounded a little better so I cut my upstream cats to try and see if the sputtering/stalling would go away and it didn’t help at all!

I know multiple brains are better than 2 so please let me know any test processes/where to look next. I am truly stumped. thank you in advance!
First off. Stop unplugging stuff to see if it runs or dies. All that's going to do is exactly what it did. Thats a myth! You need to do a proper diagnosis on it. OHM it out and take voltage readings.
 
Was this manual before the rebuild ? For 4R70W transmissions there are 2 different execitor ring styles that mirror up to different PCMs... I tried swapping my old side for a newer one and had same problem... there is a company that makes a plug and play module that can run the different trannys but ended up jus rebuilding my old one....that may be the culprit...there are more teeth on the gear and the sensor cannot dictate speed calibration properly... sputtered and barely moved... hope this helps as a starting point...if you try to switch pcms there is another sensor I belive that needs to be added to the harness...if I remember correctly...been 14 years ago..