when traveling at 100km/h my raves will be at 5000rpm what could be the problem

not sure if you're in WV or not,but if so AAMCO use to do a free diagnoses..maybe see what they think..i'll bet at 5000 RPM at 100km/62mph,don't take very long to run out a tank of fuel! if i am going 65 mph in my ole 2000 F150,i'm at 1650 RPM and i use the cruise every where i can, i have to get it over/at 45 mph before overdrive kicks in. good luck with it!