It has almost 87,000 miles on the 5.3L. I have noticed that during idle it doesnt stumble but is just not very smooth. I know it needs a tune up anyways. I have some questions. What needs to be replaced during a tune up? Kinda new at this. I just did a oil change on it Spark plugs? Which brand? Spark plug wires? Which brand? Fuel filter? Differential oil? Transmission flush? Transfer case flush to? Anything else I'm forgetting? Any advice is much appreciated!