Hi. Hoping someone out the can help. Sierra 92'mdl. Ever since i bought this a few years back, the engine idles fine, however when the lights and/or the heater turned on, revs/idle increases (and stays at high revs) until i turn them off. Ok for when driving along (and i don't use at night anyways), however when come to traffic lights etc, the car is revving and could potentially be a unwanted cruise control... Hopefully simple

?? Thanks in advance here
