'71 rochester idle problem

As far as jetting i suppose going up one size if you have it apart wouldn't hurt. Not sure if it would help? You just don't want to go too rich in a stock application. I think there is another issue causing the problem your having. Probably a good idea at some point to tear it down, clean it and install the new parts from a kit. As simple as this sounds, i've seen these carbs lose the seal at the base gasket and caused enough of a vacuum leak to wreak hovoc on how they ran. A quick snug of all the mounting screws and even the air horn (top screws) is a easy check to see if it makes any difference. Not your exact carb, but you get the idea.......