Hello, I am having the same exact issue. 2005 Pacifica with 3.5L and 75,000 miles. Codes are P0300 and P0306, which means cylinder misfire, specifically number six. This happened about 10,000 miles ago (engine light came on). I read about a specific problem with carbon buildup on the valves in this engine, mainly due to a faulty spring retainer design. Chrysler has issues a service bulletin on the known issue. I used some Redline s1 fuel system cleaner with a full tank, engine light went off, I cleared the codes, and it stayed fine for like I said about 10,000 miles.
But engine light came on again recently, and the codes were the same. A new issue now is that the motor will not rev past 3000 in neutral or park, even if the car is rolling in neutral, exactly like what the original poster describes. When driving, it revs fine all the way to 7000 (red line) when I hold back the trans by using the auto-stick for shifting.
I did use the fuel system cleaner again, and the engine light is now off, but I did not clear the codes, and the rev problem in neutral and park is still there. I guess I can live with it, but I know its not right. Any ideas for instance why the rev limiter is doing this at only 3000? Is the PCM doing this because of the misfire codes?
Thursday, April 14th, 2011 AT 1:26 PM