If the D light is flashing it means you have a trans dtc its like your trans cel. Check it to be shure. If it is I can help you pull a code this will pin point the problem.

Change you fluid twice just to get some of the old stuff out.Run it a min. or 2 after the first fluid change. When you drain and fill the trans you only change about 3 quarts of atf the trans has about another 3 quarts in the tork converter that is still old. You see what im saying?

Do a stall test.The search button for this site is on you top right.