It's a well known problem. Please search the forum. Many detailed posts on what to look for and what to replace. Not a hard job for a DIY guy!!
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Yes search... But what ever you do, ignore the comments about using silicone sealant on the coil packs! Unless you also read the comments from a user called "BRUTAL" where he explains why that is not a good idea.....

 

Don't neglect it - raw fuel is being burned in your cats and may destroy them. Not worth the risk. By the time the CEL (MIL) is on, it's a bad misfire.

 

Check my thread called "Misfire Issues" which I believe was last updated today....

As previously mentioned, the Jag tech named "Brutal" has offered a number of ideas that are well worth considering in an effort to reduce these misfire issues (especially on cylinders 1, 3, and 5 on the passenger side of the car here in the U.S.), many of which seem to be caused by blow-by oil getting into various engine components where it doesn't belong. One of the recommended steps to take is to consider replacing the two original yellow-colored Intake Manifold Tuner O-rings with the new-and-improved green-colored O-rings. The original yellow O-rings are not large enough and over time, they'll break down and begin allowing oil to seep through. The new green O-rings are larger and apparently better engineered. They stop these particular leaks immediately....

Rick (known as "joycesjag" here on the forum) changed his O-rings early this year and put an end to his particular oil seepage problem. Perhaps he'll chime in here and give you some additional pointers....

 

Er... which engine? 2.5? 3.0? 4.2? SC? (Sounds like the 3.0 just from the fault!)

 

Good point JagV8! I forgot to ask that!
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