P1390 means cam/crank not in time. Probably slipped a tooth on the cam belt (Installed wrong most likely, easy to do) or, just a chance, cam timing sensor is bad. Take it apart and look.
Alternator going bad..replace it. Just had the same thing on my 2000 neon
Trouble code P0743 means: Torque Converter Clutch Solenoid Circuit Electrical
Go to www.the12volt.com they will have your wire diagram for free.
Trouble code P0551 means:Power steering pressure sensor circuit range/performance
Trouble code P0405 means: EGR Position Sensor Circuit Low Input
Trouble code P1391 means: Intermittent loss of CMP or CKP what does cmp or ckp stand for
Trouble code P0742 means: Torque Converter Clutch Solenoid Circuit Stuck On
Trouble code P0449 means: Evaporative Emission System Vent Control Circuit Intermittent
1684 The battery has been disconnected within the last 50 starts
Misfire in cylinder #2
Cylinder #2 misfire
The airbag light stays on when the computer has detected a malfunction and set a code. Clearing the code with out repairing the failure will not shut the light off.