Conversation so far:
What happened in 1989?
By spring 1990, Scholz was back in the studio working on the band's fourth studio album.
what was that album called?
Delp co-wrote with Scholz and David Sikes the song "Walk On", which eventually became the title track of the new album.
was the album successful?
CANNOTANSWER.

Question: did they produce any other music?
Self-contained rewrite: did Boston  produce any other music, besides Walk On?