car died when clutch was pushed in

[US Soldier(stang 98)]

well i know i posed this a long time ago like last month. my mustang is very moded with a custom tune. well the car would run/idle fine until you pushed the clutch in to down shift. my dad drives the car for me as of now cause I'm in Afghanistan tell the end of the month. well my dad drove the car over to our ford tech and the o2 sensore on the right side was bad, well the computer was trowing a fucked up code and kicked the tune outta of the car.

the stang is in the shop right now and it should be done tomorrow night