I have an 88 gta that I picked up a few weeks ago and have had promlems with it running smooth, I was changing plugs wires, and header gaskets and noticed that the engine would idle down and run rough once I closed the hood and would clear up when I opened it back up. I checked to see if it was hitting anything when closed and all vacuum lines were clear and isnt hitting any electronics. Anyone have any ideas what it could be?