need help with my 86 SI

got a few problems....
first off... i don't know how to adjust the idle. i know of the fast idle controll valve... but just as it says fast idle...-"warmup idle"

secondly ... the car has a tendancy to drop in RPMS down to 500 or lower if coasting or just sitting there not on the gas... it will not hold a proper idle... maybe i must adjsut the idle still but... that corresponds to above...