Got a 99 Windstar. Recently it has been shifting oddly like trying to downshift between 1st and 2nd. This is also causing the trac off light to come on. The codes have read that it is a TPS error but how can this act up the transmission?? Would replacing the TPS stop this or is there a deeper issue? From what I've read in several manuals and posts online, everyone suggests that simply changing the trans fluid could correct this problem. Getting different stories here and want to try to pin down one.