OK, my 2002 Volvo S60 misfires quite often now. At first the code reader said that cylinder was misfiring, so I changed the spark plugs (they looked pretty bad to begin with). Cylinder #4 still misfired after the spark plug change. After that I had the fuel injectors tested and they seem fine. I can hear the injectors click when they have power running through them and they were not clogged.
But here's the kicker, after I reinstalled the injectors with new o-rings, the code reader said that cylinder 1 was misfiring. So the nest thing that I did was swap the #5 and #1 coil to see if the coils were bad and erased the error from the computer. I read the code a few minutes later to find that the computer still said that cylinder #1 was misfiring. So I then gave up and tried doing some research and found nothing.
Today, after I jump started the car, I read the code and it said that now cylinder #5 was misfiring and not #4 or #1.
Now I am completely and utterly confused on how the misfire just moves around like that. Could it be one of the two computers failing? Or could it be something else?

 

You can all disregard the message. It turns out it was an ignition coil and not the computer. Someone else in the house swapped the coils when I was not looking which gave the different cylinder readings. So I went to an auto parts store and bought a new coil and it works just fine now.

 

Good post.