shaky 1st gear, hard to start,

[69mach351]

I so much appreciate the help I have recieved from this forum. My mustang has gone for two-days problem free. I enjoy driving it as much as I enjoy the ladies looking at it. I burn rubber even when I don't intend to. The only thing is that whenever I get the car going the engine shakes. ( idles at 700). Once I get to higher RPM's in first gear the problem is gone. (it doesn't shake if I rev high from first but the tires spin, I don't think that the cops will like that excuse.) Runs fine the rest of the gears. Another thing is that I have to put my foot down on the pedal to start the car, I believe that it is because my choke is brocken. Not positive. Are these related? If it is not the choke then maybe the thing that makes me put my foot down on the pedal is what makes it shaky? ( too rich, lean fuel???). Anyone who has experienced this or who has any input, I would appreciate any help. Thank you, David