I have a 3000 PSI Honda pressure washer. The motor

any hosue holdcar motor oil will work

http://www.ppe-pressure-washer-parts.com/files/1961581/uploaded/020488%20man.pdf
This is for the Briggs and Stratton, basic operations should be the same for the Honda engine.

You should have two fuel lines going from the carb to the tank, one has a filter,

make sure both lines are good without any breaks or cracks. if the filter is dirty

you may need to replace it. you can fish it out of the gas tank by making a hook

on a wired coat hanger, try to remove the filter and put the line back in the tank

make sure they are both submerged, if it runs just replace the filter, good luck!

there might be a broken piston in the pump.
you will need to check each one & replace the faulty one.

Your pressure relief valve may not be working. If that happens when you shut off your spray gun, then pump is dead heading, stopping the motor. If this is the case it stops dead, not coasting. Either replace the pressure adjusting relief valve or remove it, and disassemble it and clean it.

Check your manual to see if it call for premium or regular. Premium has less energy per gallon and is designed for higher compression engines. What makes it "premium" is more anti-knock compounds - not better quality or performance. Sounds like a vapor lock problem that resolves as the engine cools. Regular gas may help with that.

check the govenor and make sure that it is free to move

check your fuel mixture settings on the unit. What is the model of the engine?

This may not be a motor problem. It sounds like your pump is not working properly and the motor is just following the pump. First thing to do is check for leaks in the pump, wand hose, gun etc. It may also be a blown water seal inside the pump.

Honda engines are know to be very well and durable.