sounds like your vacuum lines arent hooked up right. there's a modulator with a hose that goes a hardline then goes to carb. try f**king with that and see if that dont fix it. my friend has a 73 f100 390 and he was having the EXACT problem yours is having.
sounds like your vacuum lines arent hooked up right. there's a modulator with a hose that goes a hardline then goes to carb. try f**king with that and see if that dont fix it. my friend has a 73 f100 390 and he was having the EXACT problem yours is having.