Hi, the diaphragm in my center Holley 2300 (six pack) needed replacing because it got hard and stopped working, but after changing it the engine starts and runs fine but won't idle - it just slowly decreases rpm and dies. It's a 440 automatic if that makes a difference. I verified that everything was reinstalled correctly and it idled just fine the last time I started it which was probably 1-2 months ago. I'm guessing that I need to take it apart and clean it out?

 

Sounds like you might have a vacuum leak?
Did we change the base gasket also?
Check to make sure you did not crack one if the ears on the base plate when you re-tightened the carb.
Make sure all the lines are in good shape...

I agree with you... Should have been kind of an easy fix, being you dont have to open the carb up to change those parts. But you could be rite, but sometimes as soon as you turn them over, you just send that crud everywhere !!! So you could be rite, Might just need to open it and freshen it up, as well as the other two....
Keep us posted...