viking2869

I have a 1998 f150 5.4l v8 and I have tranny problems

1) when taking off from a stop my transmission wont shift to second unless I let off the gas and it will shift if I dont let off the gas It will shift at around 3500 rpm and its pretty harsh causing the O/D light to start blinking

2) the other problem is when I am at crusing speed seems like I have no acceleration and if I try to kickdown the engine revs and slams into gear also causing the O/D light to start blinking

I had the codes read and got a p1715 I was told that is the sift solenoid what do you guys think? dont want to waste money on something I dont need could anything else be causing this code