2005 Chrysler 300

2005 Chrysler 300 6 cyl Two Wheel Drive Automatic 104000 miles

my car is misfiring at 60-70 mph, the light came on but went back off. When I took the car in to have the code read they told me it was misfiring. Cylinders 3-5 were the worst they told me. The garage then told me there was a carbon buildup that they would have to fix so they did a carbon wash, and replaced the map sensor. This set me back 300 dollars but it seemed to fix the problem, for 2 weeks. Now they say they have to rotate the valves and do another carbon wash, which will cost another 700 dollars and they say that there is no guarantee this will work but they say they have fixed this problems on other cars. Can you tell me are they on the right track? The car has 100000 kilomaters on it and almost all have been highway driving. Im from canada and have driven this car to las vegas 4 times florida 2 times and new york 2 times totaling aprox 60000 thank you.
April 10, 2009.

In 25 years of working on cars, I never heard of rotating the valves. Take the car to a nationally recognized parts store and have the scan the computer. Let me know what they find.

I received a reply from another person, who told me about a tsb for the chrysler 2005. It mentions the misfires and gives you an resolution, which when they put these motors together they put the wrong springs and locks on the valves. The carbon buidup is normal with this motor. And they have to replace the springs and locks and do a carbon wash. I did this procedure and it fixed the problem and then I traded the car in on a new car.

May 4, 2009.