We just bought a used 2005 Jeep Grand Cherokee with 33,000 miles on it. We drove it before we bought it and everything was fine. On the way home, the check engine light came on. We took it to the dealer since it is still under warranty and they said the code showed it was a random misfire and that the plugs needed to be changed. I took it to another place to have them changed and they said it cleared the code. Well I drove it all day today and everything was fine but once I got home the check engine light is back on again. Any one know what might be the problem or of any TSB's for this? I am going to take it back to the mechanic for diagnosics again in the morning.