I have a 2000 zx2 w/ 70k miles on it. It sometimes stalls when I'm stopped at a light or stop sign and the RPMs fluctuate between 900 and 11k and its just really rough (more than the usual shakes). I replaced the fuel filter and spark plugs. Could it be the vacuum lines I looked at them they are old and a little cracked but no visible holes. I could use a little advice any ideas guys?