Mike Sekowsky writes and pencils Phantom Stranger 6 (March/April 1970), with Vince Colletta on the inks. Aside from the Neal Adams cover, this whole issue feels like a big step backwards.
The kids are in it again, coming across a spooky house, apparently suffering a poltergeist infestation. They phone up Dr. Thirteen, who comes to investigate, and the Phantom Stranger shows up as well. It's an awkward lead in.
Then things get worse. For some reason, Sekowsky decides to revert to the older formula, and has Dr. Thirteen tell the kids a completely unrelated story about a phony haunting he exposed.
The Phantom Stranger then counters this with a legend of a headless horseman, who he helped find his missing head.
Then the Phantom Stranger accuses Tala of being behind the poltergeist situation. Sure enough, she is there, but was just sort of hanging out behind a curtain, and not the one responsible for it at all. It turns out that one of the two elderly sisters living in the house is a witch who has been casting spells to torment her sister for childish reasons.