I just bought this machine for my wife and she has not been able to drive it yet due to this issue. The machine starts fine and idles fine. If you accelerate steady and slowly most times it will move but if you depress the accelerator fast the machine just shuts off. Only other thing I noticed is the problem seams to get worse when the machine warms up to running temp. Please help.

[2015 Z Force 800 53/Trail EPS]

Check the fuel supply and pressure. Also check the coil voltage and the CPS. Never hurts to take a compression test and check the valve lash either.

Clark's advice is always solid, but assumes a certain level of mechanical aptitude which I can't detect in the description. How experienced are you with fixing engine issues (of any type)?

What year is the machine, and how many miles?

I'm going to assume that you can get it up to speed under slow acceleration and it rides normally unless you stab the accelerator. Is this correct?

Does the engine spin up quickly in park/neutral when you stab the gas pedal?

There are "backyard mechanics" tests that can help narrow down the failure point, like testing engine management by manually adding fuel to the intake and seeing if the engine responds well to quick throttle under that condition (in which case, compression/voltage/coils are all working).
But this takes some experience to know how much (or how little) to add, and I'm reluctant to advice this technique to the inexperienced out of an abundance of caution.

What you describe seems to me to involve engine faulty engine management (sensors) not responding to change quickly enough. TPS and  MAP are the usual suspects, but there are other possibilities as well.

There are lots of ATV shops in your neck of the woods that could probably diagnose this fairly quickly.