RPM oscillate when idle!

[lifesnotfair]

Hey all,

My revs kinda oscillate when I'm idle. When I turn A/C they kinda go up a bit, to about 1000, without it it goes down to about 700-800... but they kinda dance in there, ya know... and it's not just a bad tachometer coz you can feel it in the car actually.

I know I have an escape somewhere in the exhaust (maybe the exhaust manifold gasket or I don't know what), and a mechanic told me it could be the spark plug wires.. he even told me those wires don't even seem like the stock ones on my car, because the tips of them don't go all the way "in" the head... What's a good set of wires for me to order? I changed all the spark plugs a week ago.