81' datsun kingcab high idle/dieseling

[zlich]

okay so here's my problem my datsun has a high idle even though its turned down it looks like the return spring on the carburetor is bad but I dont know because I tried fixing it with a different spring and it didnt do anything. it sits around 1K on the tach and when I press down on the gas and let go it sits at 2K. but when I go under the hood the piece of metal attached to the throttle cable when i push down on it goes back down to 1k. any ideas? my uncle says its a sticky throttle cable but when I unhook the throttle cable it still does it. also it diesels really bad I think it might have something to do with the idle problem but i dont think so cause it still does it even after I have it at a normal idle just not that bad. it has a brand new z24 that had 8 hours on it when i first got it now its probably got around 13hours on it and for miles all i can say is around 309+ and it had sat for 7 years after it ran for 8 hours.