IMRC plates. Secondary intake port butterfly valve. Kind of like Ford's version of VTec on 96-98 Cobras. Pop off your intake, and install IMRC delete plates. Or, you can clean them and just keep on going. Most folks like them off.
Ummm..... the last time I checked you dont have to pop off the heads to put deletes in.
OP- Could be your IMRC controll box or they are just full of crud that they are sticking open. There is a write up on how to clean them somewhere. Just do a search and you will find it. Also if you want to go the delete route then now would be the time if your gonna clean your IMRC's. Hope that helps.