I own an 83 zx turbo. It idles rough when cold. Cannot accelerate when cold. Have to wait about 10 minutes warming up before driving. Have replaced injectors, cylinder head sensor, O2 sensor, airflow meter, and have repaired AAC valve. Have also replaced spark plugs, cap and rotor and wires. Air regulator appears to be working. Intermittently, it will backfire under load. Suggestions please!!!