I've recently put full mp3 support on my system, but amaroK isn't playing it back. I've uninstalled (erased) it off my system and reinstalled it, but still no mp3 support. I don't think I'm completely uninstalling it though, because the first-time-use walkthrough and setup wizard didn't come up.

The wierd thing is that I can play the previews of the mp3s I try to place, but as soon as I select and open it, amaroK tells me it cannot playback mp3s and asks me to adjust the engine I use. I assume I'm using GStreamer, but it doesn't show up in my Engine drop down list (bug?).

Any help would be greatly appreciated.

You didn't write anything about ur linux distro but i would try choosing different engine - try arts or xine engine and it should work - gstreamer engine doesn't show up if ur amarok was compiled without gstreamer support.
If You are sure You have all needed gstreamer filres u can try to recompile amarok