If your gauges are fine, don't cut the line, unless you LIKE throwing money away. Try some penetration overnight. It took two days to get my steering wheel nut to finally break loose. Have patience, even though it's hard when you're working behind that small dash space. I don't have a recommendation for which way is easier to remove the harness, I will defer to someone with more experience. Also, run a search in the "Electrical" section, you might get lucky.
