1988 Chevrolet Camaro code 43

Replaced knock sensor,still get check engine light that comes on under heavy throttle then runs rough.Where is the electronic spark control module located?
If i turn the ignition off and restart the engine the light will stay off until more throttle is requested.I have already changed the "ecm" also full tune up,plugs cap,rotor,wires,ignition module,temp switch,coolant temp sensor,ign.coil.