Yes, you installed a stiffer spring. Now the mixture will go rich at 7" of vacuum instead of 5" of vacuum. In other words, it will take less throttle to make it go rich.
But that's when underway. It doesn't change anything at idle. Nor do the jets or rods. Just the mixture screws. So the foggy garage and burning eyes don't have anything to do with jets, rods, or springs.
As for the stumble when "getting on it from cruise", that depends on how quickly you move the throttle. If you move it quickly and significantly then that is likely to be not enough accelerator pump. If you are moving it slowly then that could be the springs, rods, or jets.