Q: 5.7 motor idles at 1800 rpm. will not drop down til warm and restart. on 1995 Chevrolet 3500 Pickup

Rookie cbe0621eac06868b3efe0d8d1d3611e23c60d3114864ea2ec19a68cfbd3eebab
then it takes about 20 seconds to idle down to 800 rpm. have replaced all components with no luck
(1) Answer
Vacuum leak or IAC, air is getting inside of the intake from somewhere it isn't supposed to!! Or to much form where it is supposed to.
Good scanner and operator can find this problem. Not a parts store employee with a code reader.