700RPM is within the normal range for idle on an SC. In park or neutral, it may bump up to around 900RPM, but in Drive (AOD) sitting at a stoplight, the RPM's should be around 700. Rough idle could be caused by many things. Running some injector cleaner through the system is probably a good idea, but it may not solve the rough idle. Also check the plugs, wires, electrical connectors on the coilpack, DIS, throttle position sensor (TPS), and take a look at the MAF sensor to see if it has debris on it. Another cause of poor idle and performance is vacuum leaks at the intercooler tube connections. It is generally pretty difficult to pinpoint the source of this kind of problem, so a good overall cleaning of all the ignition system and sensor connectors along with a coating of dielectric grease should be part of your general maintenance routine. That along with re-sealing the supercharger and intercooler connections will remedy most "bumpy idle" problems. If that doesn't solve it, invest in a code reader (about $30.00 from Walmart) and check to see if there are any fault codes.
Just my $0.02.......