I would have swapped the coil pack to the front and put 2 new plugs in the back.
( Front is easier to get to the plugs ), then run a couple of thousand miles and checked both front and back plugs.
If fouling still occurring, it is NOT electrical ( unless for some strange reason the PCM has a burned out transistor for that coil pack ).

Compression test time .....

180's probably right - broken ring.