Did you make sure to line up the ticks on the throttle lever with the slot in the shaft where it was originally? One tick mark off could cause that problem, especially when coupled with the heavier 366 spring and a turned in fuel screw. After everything I did to my pump, I took the low idle set screw out entirely to drop it back to a decent rpm at idle. My motor teeters dangerously close to runaway if you mash the accelerator to the floor, even if just for a second, when I'm in neutral. If I wind it up to over 2900 in neutral, it'll hover there for a few seconds once I take my foot of the pedal then start to slowly drop down until about 2600, then drop back to normal idle from there.