Ok so ive searched and searched and cant find anything like my problem so here it is i just put on a new 750 edelbrock on my 383 and got it idling right but as soon as i shut the hood my idle increases to about 2000rpm, im lost any help would be greatly appreciated thank you.

 

What air cleaner did you use?

 

Sounds almost like the hood is hitting the air cleaner which in turn is pressing on the throttle arm.