if it hasnt had a tune up in a while..please do so...new plugs,wires,rotor and cap...also you may need a egr valve,sometimes youcan remove these and clean them with carb cleaner,and they will work fine..tho you may need a new one....use the charts below to help you with this

Before replacing ECM, use an ohmmeter and check the resistance of each ECM controlled relay and solenoid coil. For example TCC etc., refer to Chart C-9A ECM QDR Check Procedure. See ECM wiring diagrams for coil terminal identification of solenoid(s) and relay(s) to be checked. Replace any solenoid where resistance measures less than 20 ohms.

Code 43 can be caused by a faulty connection at the knock sensor at the ESC module or at the ECM, Also check CKT 485 for possible open or short to ground.