1976 cobalt 235hp 5.8 ford starter issues

Hello, had an issue with the starter sticking on. I turned the key to start the engine and when I released it, the starter continued to run. I quickly killed the batteries and the engine never started. I did some voltage checks and I had 12v on the starter side as well as on the trigger even when key was released. I disconnected the trigger wire that runs from ignition switch to starter solenoid, and the starter engaged on its own as soon as I turned ign switch to run position. I replaced the solenoid and now my voltage readings are very erratic, and the relay will not function with the key, but will function if I jump it manually, so it has the capability to work.
I separated the 2 big electrical connectors on top of the engine, cleaned them, and tested for continuity from ign switch to solenoid, which was good.
Measuring voltage at the back of ignition switch, I get proper voltage at the proper time, (battery, ignition, and start). However, when I plug in the harness leading to the shifter, and engine, I get erratic readings.
Just wondering if anyone out there has had a similar issue? I have 30 years working on cars professionally, and typically would look for a bad wire or faulty ground when electrical systems go wonky, but this one has me somewhat stumped.
Is there anything special about the starter relay on a boat vs a ford car? Looks like a standard ford starter solenoid to me?
Any advice would be helpful.
Thank you in advance!

Update:
If I disconnect the ballast resistor, the relay functions as it should. I am getting 12 v through both sides of ballast resistor, which I would guess is no good. However, If I check resistance, it is 2.2ohms. Any thoughts?