Car is a 1990 miata 1.6l. I was under the car adjust my clutch pedal when I saw that the cruise control clutch pedal switch was unplugged and someone cut the connector off and just had the brown and white wire and black wire dangling there. 1st question why does my car even have that switch if I don’t even have cruise control on my car. Don’t think it ever did have cruise control. 2 will that do anything if it’s just unplugged like that. I have a mega squirt ecu so I kinda doubt it Thanks.

 

On the NA chassis, cruise control was it's own circuit with it's own computer controlling it. There is a servo in the engine bay that is vacuum operated and physically pulls on the throttle pedal in the cabin to maintain speed.
I don't think cruise control was offered on any 90 model year miata. It is possible the previous owner of your miata bought the switch online and attempted to use a stock switch to wire it to something else. Either way, it should not affect how your car drives since it sounds like you are missing a majority of your cruise control parts as it is.

 

My 1990 has stock cruise.

It should affect how your car drives if it weren’t for the MS. That switch is on the same circuit as your neutral switch. If either the car is in neutral, or the clutch pedal is depressed, the stock ECU will know about it. It uses it for DFCO.

Since you’re on MS, it doesn’t matter.