Michael SE

I had the same issue. Cylinder 4 misfiring. I changed the spark plugs (time consuming as you have to remove a lot of parts to access the plugs), misfire continued. Changed the coil on cyl 4, the misfiring continued. Changed the injector an the misfiring continued. Finally, assuming that what I had was a dirty valve, added an engine flush from STP, ran it idle for 15 min and then changed the oil. I only get a misfire very once in a while. I’ll do the same treatment when it’s time for the next oil change. I expect the problem to go away by then. It cost me $20 to get rid of the issue with the engine flush.