Intermittant High Idle (1 Viewer)

[richw99]

97 LC with 290k. When cold it always starts perfectly; fast idle at 1200-1300 then idles down to 600 over a few minutes. When hot also starts perfectly at 800-1000, then immediately down to 600. Normal idle is so smooth when stopped that barely anything can be felt through the steering wheel. I drive it daily but generally only a few miles; three times over the past two months when the engine was warm(sitting one to one and a half hours after being driven) the engine stumbles on starting with rpm at 400-500 for a second or two. Then the idle shoots up to about 2000 and takes a long time to idle down. No smoke or other symptoms. Any suggestions? Thanks