If revs are bouncing it will whirr all the time now. It's if it does it at a steady RPM that indicates it's still trying to drive the throttle flap to a different position. I thought your old one already had bouncing tickover & that's why you changed it?
I think Smaky is right, the only way to tell now is to fit a brand new ISM, but I would check that the throttle body bore and flap is grit and gunge free and opens and (especially) shuts all the way smoothly first. Also that the throttle cable is routed correctly without kinks and allows the throttle to shut to the stop every time.
If you get a steady tickover at the right RPM then job done, if it's at too high an RPM then as I'm only a few miles down the road you can try my Bosch MAF to see if that's the problem. However you have never said whether you did check the idle oil fume valve to see if it was gummed solid inside and that is a main cause of steady but too high or gently wandering tickover.