[papi]

Hi all,
I am a newbie to this I just joined today. I have a question about an 1989 Eldorado, My service engine light just came on and now when I start my car it runs at a very high idle, about 3500 rpm until I put it in gear and drive a little.It then idles down and seem's to run ok.any help would be greatly appriciated.
Thanks
Papi.