hi, my 97 f150 4x4 has intermittent dash gauge failure, the tach works when it wants to, has done that since i bought it ( used ) but recently the rest of the gauges just die and then come back i disconnected the battery( airbags) took out the instrument cluster and check the connections,put it back together, still works when it wants but now when it is in gear with foot on brake it idles below 500 rpms almost at a stall..........i don't know what i hit but i need help if anybody has ever seen anything like this