I've never had trouble with plymouth after a fresh install of Fedora but I have only used a new DVD + R to do it.
I found in a post about a year ago (sorry I don't have the link) a Guru here mentioned that with a black screen or other graphics issues
that it looked to him like the normal VGA/Graphics issue that FC has sometimes and in some cases it's a bug.
He said that it can be fixed with an edit to the bootline.
KDE and Gnome3 need a lot of RAM the Guru said.
If there is another way aside from what's been mentioned: I have not found it or heard of it.
This is the only thread I found that's close to your case-
For what it's worth I once had to write to a driver developer for help.
If you can find a Fedora developer, Package Manintainers or a Fedora Engineering Steering Commitee Administrator and write to him he may know another way- Aside from that I am out of ideas: sorry-