F150 automatic tranny gear selection

I have a 2004-5.4 towing about the same,,sticker says 4500, Only thing I do is if it seems to search for a gear,,4-3 then back to 4 then down to three and i am climbing, I with take it off OD, and let it do its thing,, I have a Scan Gauge and keep my eye on trans temp.. If it starts getting hot I back off, but the computer seems to control it ok so I let it go,, not able to lock it into any gear other than Low.
If you are concerned, look into a shift kit witch will let you shift manually.. But I have not seen the need yet...