I do not understand the status of this thread. You have asked your question. No one until I have responded. Yet the thread is marked Assumed Answered.
Nonetheless, moving forward.
What version of Premiere Elements are you using and on what computer operating system is it running? In the absence of specific details, I will generalize...
Typically there are two Premiere Elements features which allow you to try for flicker correction in the file.
a. Right click the Timeline file, select Field Options and then select there Flicker Removal.
b. Highlight the Timeline clip and get to the Motion Panel expanded where an anti-flicker filter slider exists.
If you are in the Elements Organizer Slideshow Editor that comes with Premiere Elements, there is no Flicker Removal
option there that I know of. If you are dealing with photos, does a slight blur effect work for you in this regard in Photoshop Elements. Have you looked at slight blur effect even in Premiere Elements?
Please post details that will help us to help you.
Add on....Where is this slideshow with the flicker issue....are you looking at it as a DVD-VIDEO on DVD disc or are you still the slideshow creation stage, previewing it in one of these programs?