Need a little help on where to start with my rough running 2005 grand prix N/A. It just began running rough when cold and at idle when hot. It still runs strong and no problems when moving from what I can tell.

It has 163,000 miles on it. I changed out the plugs and wires at 110,000. Did the LIM around 125,000 with a nice throttle body clean.

Any guidance on where to start would help! Thanks.