I don't like to use any crankcase flush because if the pan has crud in it you will likely loosen up a lot more crud in the rest of the engine while running a flush. What you did by flushing the pan through the dipstick sounds like a good way to go without tearing it down. I have had a few vehicles come through my shop with this problem and pulled the pan to clean out what I could. It has always solved the problem but as more stuff works it's way to the pan the problem eventually returns. I have pulled the intake, valve covers and pan on one to clean it out and that worked but it seemed like a lot of trouble ($$) for a high mileage motor.