Anyone have any experience with a strong shudder feel in a 2005 FX4 4x4 w/ 5.4L. I just bought the truck about a week ago and have noticed a strong shudder when I stop at stop lights and idle while still in drive. It actually felt as if someone slighly hit me the first time I felt it. I have watched the tach on such occasions since then and notice no change in RPM's but it is something that makes me shudder every time it happens. Could it be due to air conditioner being on? It only has 9000 miles and is still under factory warranty but I was wondering if anyone else was having this problem.

Thanks in advance for any info! :rock: