Boldman and Schaffenberger sap Superman’s self-esteem in Action 578 (April 1986).
Superman attends a charity function, and meets a drifter, Joe Blohe. Their meeting is brief and undramatic, they shake hands, nothing more. But it spells disaster for Superman.
Immediately afterwards, Superman finds that people have become nasty, critical, and openly insulting towards him. It happens to him both as Superman, and as Clark.
At the same time, Joe is becoming outrageously popular. Lana Lang ignores Superman completely, and wants to put Joe on television.
It takes a while, but Superman finally figures out who Blohe is, and exposes him on live tv. He is the Parasite, in disguise, who has used his leeching powers to steal Superman’s popularity, and self-esteem. Even with his identity revealed, the crowd is still on his side.
The Parasite makes the most of this, but now that Superman knows exactly what has happened, he knows how to overcome it. By focussing on the love and support he had been given by his parents, Superman’s confidence is restored, and the Parasite gets defeated.
The Parasite sort of slips through the Crisis net, and returns in a year or so to fight Firestorm.