Having an odd issue with my 73 Duster

67Dart273 said
Hard to say. Look at the plugs. Any reason to believe the timing is off? If not, or check it, "it's likely the carb." First figure if it's lean or rich. If lean = vacuum leak or adjustment. Have you played with the idle mixture screws? What did they do?

If rich--obviously fuel leaking by, float level too high, dirt in the needle / seat, hard to say what else

Timing I'm pretty sure is good but I can double check and I don't think its a firing issue with the plugs when it is running it doesn't act like they aren't firing properly. I have messed with the mixture screws but when turning them it doesn't seem to change anything