I did a search and didnt see anything like this.....

If i pull up to a stop light the car will idle smooth at 750 rpm's for about 30 seconds then start to sputter and idle drops to 300 rpm's.

At the next light it does the same thing.

Its a 1984 12A stick
Bone stock with the rats nest.
Stock exhaust
Air pump
etc etc.......

Any ideas?

 

it can be a few things....sounds like its missing. Check your plugs/wires, if fine, it could be a controle module

 

maybe timing or vacuum problem.

 

Could be a rich idle mixture fouling up your plugs. Does it produce a lot of gas fumes at idle?

 

does it get better if you pull the choke back out? it could possibly be an issue of the cooling system. maybe your thermostat is locked open and the motor is never fully warming up.