Multiple misfire code

[fred14042]

I have a 2005 Dodge Stratus SXT 2.4L and the check engine light keeps coming on for multiple misfire code. The dealership where I bought the car at has been trying to fix the problem for over a month now but still no luck. They have changed all 4 spark plugs, o2 sensor, catalatic converter, they have done a compression test and found that the head was cracked, and fixed that but still coming up with the same code, and they have replaced the PCM but still nothing, and now they are waiting for another sensor to come in so they can change that. Has anyone ran into this problem, if so do you have any ideas on how to fix this.
Thank you
Rick