The car runs (mostly) better than ever. The new harmonic balancer works, and it seems there's no damage to the valves after all (just had the head gaskets replaced for kicks; this is my "learning" car). The Seafoam actually cleaned up the engine really well; the mechanic that replaced the gaskets (while I watched, yay) was quite amazed at how...shiny the internals were, though I did have to also get a new gasket on the exhaust reclamation (EGR?) valve. I guess the carbon buildup was all that was left.
But now: why would the PS fluid foam up? Why also would the PS whine like our old 83 Ford Ranger? I've tried to bleed the system (jacked up front of car, turned wheel to lock either side 30 times, slowly and quickly, and added fluid). Doesn't whine unless wheel is turned. Does the car use regular PS fluid, or AT fluid? Maybe I should do another power steering flush?