My Toyota 4Runner vehicle stalled on freeway in traffic but soon after I was able to drive it again. The AT/Tem light came on two days ago after a trip to and from an elevation of 2000 feet and about 80 miles. Later I check the tran oil, and it was black. I have owned it more than 8 years and 125,000 miles and have not had any service on the transmission. Total milage: 283,000. What should I do?