Hi, I have a 2001 Chevy Silverado Z71 truck, 5.3 eng, 170K miles.
The engine is running ok but has a minor rough spot at idle and when running (a minor shake). The basic passenger in the truck would not notice it (unless they were a mechanic) but I do because I have owned it since it was new (and I am an amateur shade tree mechanic).

This week I just did the 2nd tune up on it (at 170K miles, plugs & wires only) and I still have the rough spot. The 1st tune up was done at 100K miles. I thought the problem would go away with the new plugs/wires but did not. Now I'm thinking injector or coil? Anyway to narrow it down? Thanks. Steve

 

Does it have any codes? Clean the throttle body and air filter as well. Codes would be a good place to start

 

Thanks. There are no Codes showing and the Air Filter is new. Is there an easy way to clean the throttle body? Never done it.