I just bought a act x3 tuner and put on a CAI. When I was pulling up to a line of traffic I stopped and then all of a sudden the car lurched forward and rear ended the car in front me. Has antibody else had this problem. I'm driving a 2006 Mustang GT 4.6

 

Surging issues are well known on the 05-06. Typically it is dirty throttle body and/or fuel filter.

 

If you've never had surge problems before the tune you should call the company that provided that tune. It's in yours and theirs best interest to be safe. It might also be wise to recheck all mods installations for proper assembly. I would think an improper cai installation would cause a check engine light to come on after awhile.