First thing we did was a compression test on the engine. Here's the results:
cyl 1: 125 psi
cyl 2: 120 psi
cyl 3: 125 psi
cyl 4: 115 psi
cyl 5: 115 psi
cyl 6: 120 psi
cyl 7: 115 psi
cyl 8: 125 psi
I then sprayed some oil in the low psi cylinders and retested with negligible improvement. (So that means it's the rings, not the valves - more on this later).
Since there was more than 10% variation between the highest and lowest pressures, it was time for a freshening.
I unplugged everything rather uneventfully in a day and got it out of the engine bay with the help of the wife and the kids.
