I may have missed it in the beginning of this thread, but generally there is a lot of times there’s an issue with grounding, whether it’s a wire or the sockets themselves. I’ve had that issue on a couple Firebirds.
86 Pontiac 2+2 69 Firebird Coupe(Under Construction) 69 Firebird 4 speed Vert Driveable but Under Construction 64 1/2 Mustang (Under Construction) 86 Z28 Convertible Weekend driver