Video frame rate is horrible in export but fine in preview

Hi all, I’m new to editing in premiere pro. I have a 9 minute video from my GoPro that I’m trying to edit. I have added a posterize time to the video, set the frame rate to 1.5, then set speed/duration to 1500%. In the end it turns out to be a 38 sec video in the preview. When I export the video, it exports to a 2 minute video and the video is choppy and it’s not the same as the preview. What settings should I be exporting it as or how do I export it properly????

What can I do?

I’m running a 2016 MBP. Original video is about 9 minutes long without any edits. After edits it is 38 seconds long.