overheating 25hp

[rabbitrunner]

Hi i have a 97 25 hp that is running hot on me I have changed water pump tstat and head gasket but still seams to run hot. Temp is around 155-160 on the block. Also i noticed that the pump pumps in spurts till tstat opens then pumps a steady stream till it closes again. Any ideas would a help.

 

[Rocketman14]

I am not a professional boat mechanic, but I would check the intake screens on the lower gear case, take the t-stat out and drop it in some water heated to the set point of the thermostat to make sure it opens at the correct heat range.
If that doesn't tell you whats wrong I would drop the lower unit and double check the water pump. Make sure the key in the impeller didn't slip out accidentally. Also check all of the water tubes and passages that you can shine a flashlight down or through to make sure old rubber inpeller pices hasn't plugged things up.
What did the old impeller look like?