While Elvis-style sightings of Jim Morrison are rare, there is more to life after death for the Lizard King than Oliver Stone's The Doors. Writings Morrison left behind are fueling a second career for the Doors' drug-besotted leader, who died of heart failure at 27 in 1971. More copies of The Lords and the New Creatures a compilation of Morrison's musings and verse first published in 1971 have been sold in the past three months than in the previous three years. Another volume, Wilderness: The Collected Writings of Jim Morrison Vol. 1 is selling briskly in its third hardcover printing total copies: 151,000 quite an achievement for a book of poetry. ''Amazing, considering there's a cheaper paperback version available,'' says Villard's Peter Gethers. Most of the new readers are kids, ''the same age group that liked Morrison when he was alive,'' Gethers adds. A newer collection, The American Night: The Writings of Jim Morrison Vol. 2, is climbing the trade charts and will be out in paperback this August from Vintage. Morrison's versifying may not rate high with some critics, but don't tell that to Duke University professor emeritus Wallace Fowlie, 82, whose lectures on Morrison's poetry are SRO. Says Fowlie, ''His poetry is not unlike Rimbaud's.'' Fowlie, who once received a fan letter from Morrison praising his translations of the French poet, also adds, ''But I'm not going to say any more than that. I'm writing a book about Morrison.''