i have a 1985 with a 12A and it wont idle. it starts well and it runs ok but if i let off the gas it just dies.

 

I sometimes get the same reaction from my 12a. It'll idle fine but after some spirited runs for no reason whatsoever it'll turn off. I'd say check your timing. Thats what I need to check.

 

Have you tried adjusting the idle on the carb? Seems like the logical place to start... And welcome to the forum, your life will never be the same...

 

i know when i final got my air conditioning working my car wouldnt idle. got the screw adjusted then it worked fine. now i decided i dont like AC anyways and now it idles high. o-well

 

mine didnt idle well eather espacially if it was hot outside I cheked everything and it was the throttle cable that was loose and it would close it off completely and it would die I got that tintened up and it idles at 800rpm steady.

 

I don't know much about FB's, but I had an FC with a similiar problem, turned out to be a disconnected vac line. Just a suggestion.

 

i have an 85 and it wouldnt hold an idle. I didnt mess around with it much, i just bought a holley carb and it idled fine...make sure to check all your vaccum lines and make sure the throttle cabe has enough tension on it.