Hi, 
  
This is my first post here.  I searched the forum and couldn't find an answer, so I have a question for the group.  Yesterday morning I drove my 1991 Subaru Legacy to work, and it ran fine.  I drove it at lunch, and it also ran fine.  After work, I started it up, and it seemed to be missing a cylinder, running and idling roughly.  I limped it home, and this morning began investigating the problem.  I started it up, pulled the spark plug wires from the coils one by one, then plugged them back in.  Each time, a spark would jump from the coil to the wire, and the engine would run even worse (on 2 cylinders), until I tried the last one (driver's-side front).  When I pulled this one, there was no change in the (rough) idle, and no spark jumping across to the wire.  At this point I noticed that a spark was jumping across from the body of the coil to the metal bracket in front of the coil, on the front toward the right side.   
  
Do I have a bad coil, or could it be some other problem?  Can a coil go bad on just one side?  I checked on coil prices, and they're expensive, so before I bought one, I wanted to check with everyone to see if the consensus is that the problem is a coil gone bad.  Also, if it is the coil, would it be bad for me to get one from a salvage yard? 
  
Thanks and regards, 
JWK