[san rensho]

I would add, pull the sump plate to see whats in there, especially look for any metal or plastic and sealant that can clog the oil intake tube. Clean the sump plate thoroughly. I know you just changed the oil, but you can just drain it into a perfectly clean container and re-use it.

As a preventative measure, replace the water pump if it hasn't been replaced before. They are prone to failure and when they do, the plastic impeller can break off and clog the water passages in the head leading to cracked heads. If you do the pump, then do the motor mount also, which also fail very quickly. If you do both at the same time, both jobs are much easier. If you take the radiator hoses off (which you need to to replace the pump), getting the motor mount out is much easier and to remove the motor mount, you need to lower the engine which makes access to the WP a breeze.