'06 Tundra 4.0 V6 5spd auto, tranny upshifting too soon, ATF flush?

[06TundraSocal]

Recently my Tundra has been wanting to upshift too early which leaves the engine bogging. I'll be rolling on the throttle from about 10 mph and it will be up in 4th gear. If I want it to downshift, I've got to have the throttle WFO and hold it there. When it downshifts, it takes a bit longer than it used to as well, so I have to wait about a second for it to downshift, but that's usually from 4th down into 2nd. It doesn't seem to want to downshift from 4th into 3rd with the throttle halfway open.

The truck has 98k miles on it, and had the tranny fluid flushed (or changed) at 60k. I'm considering doing it again just to see if that changes anything, along with the diff. Is there anything else I should be looking at as well?

Wanting to do it myself, but finding out that it is a bit of an ordeal on the 4.0's? Is this something I should even consider doing myself or have a lube shop do it?

Just did the spark plugs, engine oil change, air filter, oil filter, MAF and TB cleaning so all that should be good.

[ddvk]

Change air filter, do a tuneup for the injectors, clean the MAF with CRC cleaner, drop pan and replace magnets and cleanup the gunk, do a tranny flush, replace fuel filter, CHANGE PLUGS, drain and fill radiator with OEM coolant (this will remove some hot spots in the engine).

If you want to keep the vehicle for another 98K and have some money to pamper the baby, replace the coils with OEM ones.

Good luck.

[06TundraSocal]

As much as I would like to get a new set of coils for it, that's not in the cards right now.

A tranny flush isn't so simple on the 4.0's evidently, and neither is the fuel filter. That annoys me.