I’m seeing considerable wear on the center electrodes of these sparkplugs. I would expect the new plugs to make a big difference. A too-worn plug creates a too-weak spark, and that creates poor combustion and operating problems.
As the energy jumps from the center electrode to the ground electrode (the one connected to the threads), its high heat and high energy evaporates material and carries material from the center electrode to the other. That’s what creates that rounded “nub” on the center electrode.
Other than extreme wear, he plugs look pretty good actually. I don’t see any gas-wet plugs, any oil-wetted plugs, any oil residue buildup, any signs of extreme heat on any of the plugs (like heat-damaged ceramic), or anything other than the wear.