Volvo Repair: 1988 volvo 760 gle emissions, volvo 760 gle, emissions standards

Question
Failed emissions standards were HC 0.80GPM and CO 15.0GPM. The car's reading was 3.23 and 63.4 respectively. The catalytic converter, o2 sensor, coolant temp sensor,plugs,wires, cap and rotor were all changed. Fuel rail with injectors wre removed to check for leaky injector. none were found. Need some direction, can you help? The car has been to 2 different tech shops without success.

Answer
we do not have emission tests here.high HC are caused by high combustion chamber temperatures.this can be from the car running hot or could be from carbon deposites in the combustions chambers causing the high temperatures.I would try an upper engine cleaner designed to reduce cabon in the engine.