Foreigner is an English-American rock band, originally formed in New York City in 1976 by veteran English musician Mick Jones ex-Spooky Tooth and fellow Briton and ex-King Crimson member Ian McDonald along with American vocalist Lou Gramm. Jones came up with the band's name as he, McDonald and Dennis Elliott were British, while Gramm, Al Greenwood and Ed Gagliardi were American. Their biggest hit single, "I Want to Know What Love Is", topped the United Kingdom and United States charts among others. They are one of the world's best-selling bands of all time with worldwide sales of more than 80 million records, including 37.5 million records in the US.

In the late 1980s, Jones and Gramm each put out solo efforts on Atlantic. Gramm released Ready or Not in January 1987 and shortly after its release, rehearsals for Foreigner's next album had started but ground to a halt as Lou's status with the group was uncertain. But after the promotion and concert dates for Lou's album were finished, cooler heads prevailed and Lou rejoined Foreigner in the studio for Inside Information, which was out at the end of 1987. Jones had Mick Jones in August 1989, then Gramm followed with his second solo release, Long Hard Look (October 1989), and decided to leave the group in May 1990 while preparing to tour behind Long Hard Look as the opener for Steve Miller Band. After finishing this tour, Gramm went on to form the short-lived band Shadow King, which put out one eponymous album on Atlantic in October 1991.  Meanwhile, Jones brought in a new lead singer, Johnny Edwards (formerly of the bands Buster Brown, Montrose, King Kobra, Northrup and Wild Horses). Edwards made his first live appearance with Foreigner at the Long Island club Stephen Talkhouse on August 15, 1990, where he, Jones, Dennis Elliott and Rick Wills appeared, joined by special guests Terry Thomas (on guitar, who produced their next album) and Eddie Mack on harmonica.  The new edition of Foreigner released the album Unusual Heat in June 1991. This was at the time their worst selling album and only climbed as high as No. 117 on the Billboard 200, although "Lowdown and Dirty" was a minor mainstream rock hit, reaching No. 4 on that chart.  In July 1991, the new lineup of Foreigner played some European dates then made its official US debut on August 9 performing on the second night of a Billy Joel benefit concert at Deep Hollow Ranch in Montauk, New York to raise funds for the preservation of Montauk Point Lighthouse.  For their 1991 tour, Jeff Jacobs, who had played in Joel's band, was brought in as the new keyboardist and Mark Rivera returned. But during the fall leg of this tour, Elliott decided to leave the group after a concert at The Ritz in NYC on November 14, 1991 and embark on a career as a wood sculptor. Larry Aberman was then recruited as a temporary replacement until Mark Schulman arrived in 1992 to hold down the drum throne for the next three years. Scott Gilman (guitar, sax, flute) joined the touring band in 1992 and Thom Gimbel took over from Gilman and Rivera in late 1992 after they departed. When Gimbel went to Aerosmith in 1993, Gilman returned to handle the guitar/sax/flute duties until Gimbel came back permanently in the spring of 1995.

Using a quote from the above article, answer the following question: Why did he leave?
solo efforts