1990 Mitsubishi Mirage is my computer faulty?

My car was having a hard time starting when it was cold and the check engine light came on, so I diagnostic my car with a scanner and I replaced the sensors the code said were bad:airflow sensor, throttle position sensor, idle speed control motor position sensor and the coolant temp sensor. When I cleared the codes on the scanner and rechecked it, these are the codes that showed on the scanner: intake air temp sensor, idle speed control motor position sensor and coolant temp sensor. The engine light won't go off and I am still having the same problem with the car having a hard time starting when the engine is cold. It starts fine when the engine is warm. It was suggested to me that the airflow sensor that I got is bad or try cleaning the throttle body. Then it was suggested that the computer might be bad? Should I replace the airflow sensor I got or simply check the computer to see if it is faulty and replace it.
Also, I am having a difficult time locally where the computer is inside the car.