1992 325i BMW moter missing/backfiring

I just installed an after market alarm on my car and it was running fine ond every thing was ok but now it is acting like it is missing and sputtering and not wanting to run the alarm isent a remote start so i dont under stand why it may have efected the moter? but this is the only thing i have done so is there sum wire i may have cut or dissconected? it already had an alarm and i used all the same wires except a purple and brown wires they are in the same wire harnes as the yellow wire with the fuse i think the yellow is the 12v constant but not sure what the other two do??? any one have any sugestions??