yes i got it used and no i didn't hear it run

 

but i stripped it down and checked all the internals and they looked good

 

Time for a compression test.

What do the spark plugs on the "dead" side look like? Is it just spewing out raw gas on that side or is it attempting to combust?

 

Would ALL 4 cylinders on one Bank only lose compression while the other side is good? Not likely. The coil pack assemblies are an easy Bank to Bank swap on the GenIII. You can see the injector and ignition primary pulses using a low current clamp on probe like the CA-60 connected to your DVOM. You can also watch the secondary spark output using an adjustable spark checker. Look at wiring harnesses, connectors and their pins, etc.