shifter cable seams to be melting : HELP!!!!

I REPLACED THE SHIFTER CABLE IN A 1985 MONTE CARLO and an hour later it seams that the cable housing melted and came apart by the shifter. the parts store replaced the cable for me under warranty. I installed the second cable, checked all the body and chassie ground cables and even installed secondary cables to make sure there would be no current chasing a ground. I checked the cable for heat as the car sat in the driveway running. Sure enough the second cable did the same thing. It dosen't seem that it is related to engine heat and with everything grounded, I'm out of ideas. HELP!!!! Please.