I have an 03 x-type 2.5 with 170,000 miles on it and its throwing multiple misfire codes and the dreaded p0420. Lots of threads here about this but no solutions that I have found. I changed the plugs with bosch platinum plugs, intake gaskets, and both valve cover gaskets. The codes were coming up before and have never left. When its really cold out, which is not that often here in Texas, it runs like crap till it warms up then it runs great, seems like a air leak to me?

My mechanic checked the coils and said they were good then pinned out the computer and said some things didn't look right so they ordered a used computer which should be in next week.

My question is does anyone have a good answer for what is going on?

Thanks

 

Anyone???

 

No one has any ideas?