Idle has a mind of it's own

I have a 92 Jimmy 4.3 CPI. I just replaced the fuel pressure regulater and got it all put back together. The truck purrs like a kitten now and I love it.

While on my test drive I did notice one thing. When I start the truck it idles really high then gradually slows down to normal. When i pull up to a stop sign or a traffic light the idle is really high but gradually slows down.

Any thoughts on this one guys

I had the same problem with my 1998 jimmy.......and as soon as i replaced the transmission, problem was gone. prob not what you want to hear i know.