rough idle

Bought my car from a single owner 4 months ago. Bone Stock from what I could tell. Would shut off at idle. I change spark plugs, plug wires, and coil pack. no improvement. I change the MAF/AMF (whichever it is), no improvement. I hear hissing so I try to fix any vacuum leaks, in the process...

Hey Guys, My 89' gets a rough idle every now and then. The car doesnt die but will idle down to around 500rpm and idle rough. But this only happens once in a while. For instance i was driving it yesterday. Stop at a light and it was idling fine. Pull up the the next light thought it was going...