code 25?

I have a 96 sport 4x4. Took it to tuffy to get some exhust work done. When I leave the check engine light is on. I pull code and I get 12, 25, 55. I know what 12 and 55 are but what is 25? Could it have been caused by tuffy?

skog

12 Battery or computer recently disconnected

25 Automatic Idle Speed (AIS) motor driver circuit shorted or target idle not reached, vacuum leak found

55 End of codes

http://www.allpar.com/fix/80s-codes.html

How do I go about fixing that. Do I have to check all the vacume lines or is there a certain place I could start. Is it possible that this is caused by the muffler work?

skog