[Bruce Edwards]

JP,

Ok let me see if I have this right. It idles alright but has a miss at low cruise speed? If so that is a sign of a lean mix. Does the car have a manual choke? If so what you can so is drive the car to what ever speed the miss starts. Slowly pull on the choke a small amont at a time. If the miss goes away and the engine starts to smooth out, you can hear it when it is right, the jets are to small. If it starts to break down worse it is to rich and you need to back off the jet size.
Now if I did not understand and it misses as you are putting your foot down you have an accelerator pump issue. Those are a bit harder to sort out.
Let me know which it is and I will do my best to walk you through it.