Help! Ls coil issue

[black_k5]

I recently did an ls swap on my 72 blazer. It has a 02 5.3l out of a burban and I have a bp wiring harness. Shortly after I got it running I got an error code for coil c primary/secondary issue. I pulled the wire off the plug and used a new plug as a test to ground. Cylinder 3 has little to no spark. Moved the spark plug wire with the plug to cylinder 1 and it had great spark. So I swapped coilso on 1 and 3 and retested with the same results. Also when the issue started I swapped all the coils and brackets from another truck and same issue. I tested the light blue and pink wire at the coil harness connector and I have over 13 volts. I'm lost on whereach to go from here and I was planning on taking it on a trip this Friday. What am I missing?