You haven't said how you're getting the video into Premiere Elements -- or even which version of Premiere Elements you're using. (Ideally you should be using version 11 and you should have the latest version of Quicktime installed.)
Plug your phone into your computer via USB. In Premiere Elements, use Add Media/From Flip or Cameras to open the Video Importer. Set the Video Importer's source to your phone and then select and download the video clips from your device.
If that doesn't work, please give us much more detailed information about your operating system and your processor speed.
Welcome to the forum.
As John T. points out in his linked articles, the variable FPS rate in the iPhone footage (not sure of the exact circumstances, where it is applied, as some iPhone footage IS constant FPS) is likely the big issue.
As some other users have reported, if QT Pro (not sure how capable QT Player - the non-Pro version - is, regarding Saving/Exporting with constant FPS), can correct that variable FPS issue.