Drove bout 2 hrs from work got 2 a stop light and when I took off felt like the tranny slipped from 1st to 2nd. Got home let it sit for bout 30 min left home didn't happen again. Its a 2002 with a 7.3 and a 4r100 tranny. The tranny has a billet torque con boosted line pressure and a 28,000 lb tranny cooler. Any ideas