1992 Z34 Lumina stalling

recently i had to change a vacuum valve that broke. it was connected to the blower vents and the cruise control. after i fixed that i noticed that the car was acting wierd. i noticed that when i am slowing down, the rpms bounce above 1 then go down to about 1/2 then go back up and down. i know this probably has something to do with vacuum. the car even stalled out a couple of times when this happens. would this be my pcv valve being clogged up? or is it something else? thanks for any help.

i should add that this doesn't happen every time but it is bothering me now because when i come up to a stop i have to shift to neutral and hold in the gas a little bit to keep the enging running when it wants to quit. someone please help.

A clogged PCV valve probably wouldn't cause that. The IAC would tend to compensate and add idle air to maintain the target idle RPM.

More likely that another line was disturbed or damaged, and is leaking vacuum. Other typical large vacuum leaks include the power brake pooster and EGR valve.

well my service engine soon light has been coming on the code was for the egr valve.