How long of a drive? I've done 150 mile drives and noticed nothing like this. I haven't gone for that long a drive since the CAI install and tune however...

 

I was driving from Memphis to Chicago moving.... SCARED ME Bad.... I was lucky that I was on the Interstate and not on a two lane road trying to pass.....

 

I've had this problem from day one. I drive 50 miles to and from work and on two occasions I was almost reended due to this little quirk. So your saying the TSB for this problem is 06-4-9 involving the AC or did I miss something since I couldn't get the link to come up on TSB. Either way its off to the dealer tomarrow to get a appointment.[:@] It seems this car is never out of the garage over a week I just got it back after having a new head and cam installed seems the valveguides were screwed up. Mustangs you got to love them.