My Sable started to behavior wierd lately. When I start the engine up in the morning, it misses idle badly and it feels like about to die. After running a while, idle and engine works just greatly with no problem as far as I can tell. The idle RPM stays at 8 at all time. Searched a little bit and it seems to relate several things: vaccume leak, IAC valve fault (won't this cause RPM to fluctuate?). BTW, I replaced plugs and wires a couple of months ago.