So I put a brand new OEM carb on that motor. Right now when I press on gas pedal too fast it will die. I have to press it slow enough and it will run fine. I assume the problem is air/fuel mixture. What do I need to adjust? 

If you partially choke the carb, will it then accelerate as it should?
 
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I just tried and if I pull the choke out a little it runs good even if I press on the gas fast

Did you have this issue before you put the new OEM carb on?
Has it always done this, or the machine new to you?  
 
 
Ok, that confirms a lean condition on the fuel mix (or an air leak between the carb and head)
as your richening the mix with the choke partially on. 
 
Being it's a new carb and likely no restrictions it sounds like the main or other carb jet is too small.
Unfortunately, nowadays, engines are adjusted to running lean for cleaner air.  
 
There are many sub #'s for your engine, can you post it?
 
 
 
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All it says on the engine sticker is FE350D-BS25

Did you have this issue before you put the new OEM carb on?

Has it always done this, or the machine new to you?  
 
 

It's new to me. I won it at local auction. Whoever owned it before used OEM carb but there are two of them for this engine. And he used wrong one. Also they used liquid gasket instead of OEM gaskets. Before it was running erratically.  

Being it's new to you, I'd remove the intake manifold, CLOSLY inspect it for cracks
deformation, lack of gaskets or improper, etc.  
 
You can also spray carb cleaner in that area, while running and listen for any changes 
in RPMs.  That'd indicate an air leak narrowing down the issue / an issue..

Of course that sub # is the only one not showing. 
However, here's the closest one along with 
insulator gaskets, etc.  There are more than one intake gasket:
 
https://www.jackssmallengines.com/jacks-parts-lookup/manufacturer/kawasaki/4-stroke-engine/fe350d/fe350d-bs18-4-stroke-engine-fe350d/carburetor 

Later on after work I will spray it with the carb cleaner and report back the results. Intake manifold and all the gaskets are brand new. I replaced everything with new carb