Make sure your battery is fully charged. That can cause a bunch of codes for the SMG yet the car will drive fine. It can also fry that new $20 relay you bought. Odds are the car's never had a new battery and it's getting to be that time.
Other things to check - SMG Hyd. Fluid lever (covers near the intake manifold). Check to make sure all doors, trunk and hood are completely closed. Drive in S3-S6 and see if you notice any weird delays in shifting. Most problems don't really present in drivability issues unless you are in S5 or S6. As another member said, get your codes read and report back. We'll be able to tell more from there.