Trans failsafe. Possibly speed sensor?
 

I was driving yesterday and all of the something slammed underneath and trans failsafe came on. I pulled off the road, shut it off and started it again and the light was gone. I got back on the road, now driving in manual coasting at 2k rpm's in 4th and again TFS light popped on. This time no rear ended feeling or noise of any kind. I pulled off and again light was off agreeing starting it up again. I repeated the same process however coasting at 2500 rpm's in 4th something slammed underneath and TFS light back on. I just drove it home like that, locked in 3rd as the purpose of the TFS mode. It's a 2002 4.4i with 125k Tranny rebuilt at 95k. There is not any torque convertor whine at all and it shifts perfectly with no problems other than the infamous on off on gas lurch. even after starting it back up and code disappearing it shifted perfect for about a mile until TFS mode came on. This all happening accelerating from the offramp of the highway after a 45 min cruise at 75mph. Does this sound like a speed sensor or something? Seems like an electrical malfunction to me. Pretty confident the tranny is fine.