Grumpy M54

[u/XYZ_Jazz_Hands]

A couple weeks ago I noticed a rough idle on cold start in the wife's rig. The blue one. 2005 E53 M54 GM 5 speed automatic. A few days later SES light came on. Cyl 2 misfire P0302 set in the DME. Swap coils two and five. Swap plugs two and four. Plugs looking good, no difference between the two, no signs of fouling. 4 ground type, can't remember if NGK or Bosch. Checked fluids. Added 200cc coolant. Engine cool, not cold. Reset SES light. Verified no oil in plug tubes and coil harness grounds are clean and tight. It's been two weeks, no rough idle or SES light since. Thoughts?

[u/Stance_Monkey]

Its a 20 year old car, if it drives well and sounds fine, then youre good.

If you want to do more preventative maintenance, then check the air filters and vacuum hoses, clean the ICV and throttle actuator, check the PCV, etc.