Well, one of my spark plugs was out so i replaced them all with TR55's and put MSD wires in, it was really smooth for a few days but now it lopes randomly at idle again, jsut not as bad as when one of the plugs was bad..

 

How many miles do you have? I read over on ls1tech that you might need to run some sea foam through it. Doing mine as we speak, I am having the same problem.