Average compression is 140, 10% of that is 14psi, so a cylinder under 126psi(140-14 = 126) would be suspect.
Since #4 is low as well I would do a Leak down test on #5 and listen if air is leaking into #4, so blown head gasket between cylinders, not common but does happen.
Overall your numbers are fairly low for a 3.0l with 9.3:1 ratio
I would expect 165psi average.
My 4.0l with 9.0:1 still has 155-160psi with 350k.
The problem will lower numbers, under 150psi, is that the 10% rule of thumb doesn't seem so bad, the 140 to 120 you got, with higher numbers the gap gets bigger so you see that there is an issue right off.
Compression test needs to be done will all spark plugs removed to get good crank speed.
Cold engine is fine
Compression gauge may just be off as well.