I have a mild tune on my '13 Caravan. I recently rebuilt the transmission because the T/C was FUBARed. It does great except for occasionally if I punch it while going 65+. It'll screech the tires and throw you back in the seat, but next time you go to hit the pedal there's nothing. A key cycle will return throttle function. Only code that sets is C121C. Is the ABS angry that I'm making too much power? Is there a way to correct this in the tune or is it more likely my ABS module is failing?

I do have traction control tuned to gently increase from 0-50-100% instead of the stock 0-100%. I'm also running 245/65/17s which are bigger than the max size allowed by the ABS unit.