Look at the front of the driver side exhaust manifold and find the 1/2" diameter tube that leaves the front of it. Trace with tube back to under the master cylinder and you've found your exhaust gas backpressure sensor. Remove this sensor, clean it up or replace it, clean up the tube itself with a pipe cleaner and some solvent, and reinstall. Your work could prevent you from having a no-start condition!
If you'd rather just replace the sensor, the versions available are:
Models before 11/30/04
Models after 11/30/04