There is a noise that is there repeatedly when the engine is idling. Noise is gone when you remove the converter. Had repeated issues with unbalanced converters. Using washers as spacers to mount the converter to the flex plate. Sounds like your converter is not going into the back of the crank shaft far enough to keep it centered. I would check the end of the crank to make sure that there is nothing in there and I would look at the back of the crank and the centering hub on the converter for any kind of shiny spots because with the noise, there should be some movement and there should be a ware mark. Not sure why there would be a lack of power unless the converter moved enough to cause some bind in the pump. Best of luck - keep us posted.