runs fine up to 40 miles per hour then it dies out. Then I wait 5 min to start

There is no DIY recommended test or repair for this issue .. It needs to go to an auto repair facility that can hook up testing equipment then test drive the vehicle to determine if the problem is fuel or ignition related... Then diagnosis of the problem within the effected system can commence... It's basically a 'systematic' process of elimination... Any other approach has been proven to be a waste of time and money. http://repairpal.com/repair-shops