my 98 XPL stalls when it gets over 4000 rpm it will idle fine (maybe a little rough) and if I baby the throtle and keep it under 4k rpm it will run and get up to 20-30 mph but if I open it up it will go for a few seconds maybe even get up to 50+ mph but then the rpm meter just drops to 0 and it stops it starts back up after any ideas what is the most likely cause?