1999 Sable Idling issue

My 99 Sable with the DOHV engine it runs great, but I have a question, When I start the car it takes for ever for the rpm's to go below 1000, It starts out at like 1900 rpms and then after 3 or 4 minutes will rev down below 1000. I was told that it is best to put the car in gear when the rpm's are low, other wise it goes into gear so hard, I just hate waiting for it, so just wondering if anyone else has had this problem and is so any input would be helpfull! thanks again!
Kalvin