I bought a 1987 Nissan bluebird auto a wee while back. Bought it as a non runner. Managed to get it running but in park it revs to 4k on its own. In drive it revs to 2.5k without touching accelerator. I’ve tried various things and checked for vaccum leaks and cleaned the carb out but it’s still the same. I was informed on the Nikki carb the auto choke has a heater element which are prone to go. Would this possibly be my issue? If so where could I find a replacement or would I have to buy a whole carburettor?