Intermittent surge on rear bank of an83 308 qv

Recently developed a surge in the rear bank. Engine runs smoothly then a miss. If I disconnect the coil wire its obvious it's isolated to the one bank.

So, I swaped coils, ignition boxes, tested the crank sensors, pulled and non professionally cleaned the injectors (carb cleaner forced through with compressed air, they all were singing.

All the wires, plugs extenders, rotors and caps are new (even went back to original caps and rotors to see if there was an issue) no change. Have triple checked the vacuum lines.

Pulled the 1-4 crank sensor and it wasfilthy, figured as it is such a pain to change I would put a new one in so I don't ever have to do it again, no change.

I'm now back to believing its fuel vs ignition. It's only one bank so it could be fuel distributor has a bit of dirt in one of the 8 sectors or I need for the injectors to be tested.

Tomorrow I'm going to check compression just to make sure no sticking valves.
I'm sure it's something stupid, just can't get it yet. Any thoughts, ideas or tests would be appreciated.