I have a LX178 with the Kawaski 15 hp liquid cool, my problem is after I have started to mow for just a little bit my engine gets to the point where it wants to die. So I turn off the blades and choke it a little and then my RPM's go back up where I can turn the blades back on again only to have it do the same thing happen after about 15 ft of mowing. Anyone have any ideas?

Air fuel carb sounds is too lean.

Things to check
1. good fuel. The ethanol is causing many problems in carbs
2. Fuel filter
3. Needle and seat valve where fuel line enters carb
4. Float adjustment is off not allowing the bowl to fill up enough for demands of RPMS
5. Weak fuel pump
6. Bad gasket on carb.
7. Air fuel mixture is off on carb. If it doesn't smell/slightly smoke when its dying the its lean on fuel. If it slightly smokes/smell/puffs then carb is to rich.

Either or both can cause your problems and the numbered list can be that cause.