2018 Toyota Tacoma

? Does anyone have problems with pulling a trailer with buggy on it an rpm going back an forth from 2000 to 4000-5000 when you get up to 60 mph an higher

 

Use ECT and S5 or S4 to hold from shifting into overdrive. It should pull without big rpm jumps.
I've pulled car hauler and small SUV without issue on flat highways. Mountains may be another issue.

 

That's where the 3.5s make their power, so it is doing what it was designed to do. It drives some people nuts, but it's just that way.
Also, I see some SxS' with windshields sitting high up on trailers, that has to create a ton of drag, probably just as much (or more) power needed than the actual weight.

 

All internal combustion engines develop more torque at higher RPM (up to a point), but are more efficient at lower rpm. The automatic transmission is making your job easy. With a manual transmission, you have to manage this yourself.

 

What about if you ant got a trailer n it wants to do that between 2000-3500 rpm’s that and why it have to suck so much gas

 

I'm not understanding.
But again, the engine/transmission combo is doing as it was designed, the engine's power needs more RPM to pull the load. This truck is somewhat limited in that department.

 

Pulling a trailer of any significant size is require more gasoline because of the added weight and air resistance. You can mitigate some of this by paying attention to the aerodynamic efficiency of your trailer. For example, boats are generally more efficient with a top on at least in the limited experience.

 

Get a tune and learn to manage the truck better.
I'm on 295's a bunch of added weight still tow a small jet boat and don't have any notable issues. I lock it in s4 and lower my speed a smidge it only stops to third on steep hills as required. Typically adds 3-5 L/100km worth of added fuel consumption pending wind and hills.
And don't use cruise. It will run in 3rd constantly