Overheating and running rough

I have had some issues lately. I will start with rough idling. On start up and when sitting at lights the bike is idling rough. Thinking about new spark plugs and fuel filter. Could this be the problem or should I look at something else?
Next is the overheating issue. The gauge used to always run on the low to mid range. Now it runs just under the red line while riding. When I turn the key on for startup the gauge goes to the bottom. If I turn the key off even when the bike has sat for a day or two, the gauge goes to the middle with the key off.
I also hear a faint, high pitched whining noise coming from the engine. This noise does not stop EVER. Is there some kind of voltage draw from that? My bike has also had to be boosted after a week of non riding.

I'll be the first, helps if you indicate what year at least? I get you have an RT since you posted in the RT section.
If it's old enough it could be leaking vacuum hoses, and if it's overheating have you at least checked your radiator level?
And whining noise could low oil level.
And if it's old enough your battery could be ... tired or dying.
But if it's an '18 all this is malarky.....

From your profile I see this is a 2011 RT.
If you are referring to the dial gauges they are known to be bad or go bad and many just remove them both and let the digital gauge appear on the screen. Checking the coolant and or replacing it will be a good Idea.
If the whinning noise is after shut down it is usually the throttle body shutting down and can take up to 45 min to stop.
The rough running can be the vaccum lines to the throttle body and should be replaced with silicone hoses but changing the fuel filter and plugs is not a bad Idea if it has never been done.:thumbup:

The high pitched noise is the ECM holding the throttle plates open/closed. This will happen for up to 30 minutes. Only on the V-Twins. I do not remember why BRP made them do that. Battery draw is minimal.

Rough idle could be the vacuum hoses and would be the first thing to check.

Faulty temp gauge? Possibly. To check it, remove the 4 screws holding the dash surround in place. Unplug the Fuel and Temp gauges. Take the spyder for a drive. The fuel and temp will now show on the digital gauge. See what reading you get.

If its still reading high, check coolant level. Also make sure the cooling fans turn freely. There was info that the cooling fans can become jammed by debri. If they turn free, start spyder and let idle for 20 or 30 minutes to see if the fans come on. A dealer can test them using BUDS also. Check fuse for cooling fans(left fuse box J5 30Amp fuse).

Another thing to look at is your purge valve. This can cause the back cylinder to run rich for a few minutes, causing rough idle and even stalling. Do you smell fuel? If you do it is the purge valve. Bruce