Hi Carol Ann,
I think you're thinking of the new attraction called Sum Of All Thrills which has just opened in Innoventions East in Epcot. This is a design your own simulator ride which sounds absolutely awesome. You can choose from a tame bobsled, medium rollercoaster or intense jet, you're in control of the speed of your ride and if you want to do any loops etc. It's also very educational as you need to use maths and science to help you complete your design!
I haven't tried it out yet but after looking up some information on the web I can't wait, I've even convinced my husband who is a wimp when it comes to rollercoasters to design and ride the bobsleigh with me!
The best information I found was an article written on October 14th on
www.disunplugged.com other good information, including some video, can be found by Googling "sum of all thrills Epcot".
Happy reading and I hope you get to try the ride out very soon,
Jo