It is adviseable to take the electronics boards into account when solving problems in a car of that age/usual mileage. But the NSX is built very good and quite easy to solve compared to today's cars.

I've once had a running on 5 cylinders problem in certain conditions only for about two years. Changed some of the parts you've mentioned above like engine coolant sensor, spark plugs etc. only to find out later that one of the lower injector seals got damaged during mounting the fuel rails some time back which caused a tiny air leak and messed up the air/fuel mixture in the corresponding cylinder. Problem solved, happy car, happy owner.