Did you use LED’s any where in your set up? The slow with the headlights off sounds to me like you have either exterior bulbs not operating or there is not enough current draw to cause the flasher unit (if it’s a thermal unit) to cycle correctly. LED’s used as indicators can play into the current load as well. The indicators coming on with the headlights on should indicate exterior bulbs that are not operating. Also grounding of the column, dash frame and cluster needs to be good. I’d start with grounds and work from there. If you are using LED’s you may have to use digital flasher units. What does the system do with hazards?
