1973 Other Opel Models Engine ticks over at 2000rpm

Thanks for you're help Dave, all vacuum pipes etc in good condition no leaks, think it has given me the answer itself. Stopped firing completly removed spark plugs which were covered in carbon, cleaned them up n reinstalled. Tried starting again, was trying to start for about 5-10 seconds before nothing. Removed spark plugs again covered in carbon as before and soaked in petrol. Just waiting for replacement mass airflow meter to arrive which hopefully will rectify fault. Hopefully this will help anyone else with similar fault.