Ever since the weather outside has gotten colder my tackometer has started to read about 1000 rpms higher than I know my engine is actually running at. Doing 60-65 miles an hour down the highway my tack reads 4000 altho I know by the rev of the engine its barely to 3000. I changed my distributor cap & rotor recently and ive changed my plugs. Im not quite sure how a tack works but thats all ive done to the car recently that could have made my tack read funny. Is it just time for a new gauge ?