Dead spot on hard excell

there is not enough specif details available to be able to be close to exact But I will give an example that you can compare
in a manual transmission with a diff ratio of 3.909 and in 5th gear the rpms for 79 mph is 3200 rpms
the difference between gears is around 250 rpms so if you try to correlate the differences if it was in 4th gear the rpms would be around 3750 rpms so I suspect that the over drive section of the transmission is not engaging ( assuming that it is auto transmission)
so to answer your question , I am saying that it is too high in rpms for that speed and I suspect that the od is not being engaged as the rpms at 80mph I would be looking at around 3200-3500 rpms depending on the diff ratio

It is impossible to calculate with out knowing the over drive ratio (5th gear) and the diff ratio and tire size but with most vehicle with 5 speed boxes it should be in the 3000 to 3500 rpms range
The average vehicle at 74 miles/hr or 120 k/h runs around 3200 rpms
it doesn't matter how many cylinders or if 4x4 or make of vehicle , the rpms is tied to the ratio of the gear and the diff and the circumference of the tires
Sorry , it cannot be more exact than that

Does it cut out at 3000 rpm in ANY gear, or just at highway cruise in high gear? I ask this because what can happen is that if you spend a lot of time cruising at one speed (long-distance commuter, over-the-road driver), what can happen is the the TPS (throttle position sensor) will get a dead spot on it from excessive wear. This will cause bucking, drop-offs, a stuttering whenever you happen to hit the dead spot. Typically, timing or ignition-type problems are not going to be rpm dependent, although they may be felt more prevalently a certain speeds/rpms. Transmission issues usually occur at shift points, and not at cruise speeds.

the flat spot is a missing instruction in the CPU program in the ECM. Run the fault codes to check for faulty sensors or have the CPU program reset using the scanner. Loose wires would give a problem all over and not just at particular rpms

could be CV axles. once the joints get wore it allows for slack when stopped. jack it up and spin the tire back and forth to see if any play in axle

if you have had the tires recently check for balance ,on a SPIN balancer,that would eliminate a belt wheel,because you would see that on a spin balancer, and tire balance.But don't forget to check tire pressure too.
find a place where traffic won't run over you and from a dead start get your speed up to 5mph,then 10mph,then 15 mph,then 20mph,
what you are looking for here is the steering wheel to start rocking back and fourth that would tell you a tire steel belt has shifted or separated.
but if your **** is what rocks back and fourth then its a back wheel or tire causing it.if no rocking appears then you need to check for loose steering parts,the passenger side ball joint first.

3500 rpms is about 80 mph. Is this noise in 1st, 2nd & 3rd gear? Is check engine light on?
Chirping could be accessory belt noise. Spray them one at a time with belt dresing to see if it goes away and which belt is doing it.

You probably have a bad governor pressure sensor and solenoid.The pressure sensor is what normally goes bad ,but from vast experience,i replace both of them together and change fluid and filter.

You are spinning your tires ... read your manual ... shut off the traction control .... spin away!

SHift solenoid pressure switch