Hello, first post on here so let me know if this is the wrong area for this type of thread. 2003 4.0 xlt 4x4. When pedal stays at constant pressure the truck will always upshift or go into overdrive. Does it even when in gear "2" on the shifter. Think that means it goes intoniberdrive. The rpms drop and I have to put the pedal about 3/4 of the way down before it downshifts. I guess I should say it does the upshifting all the time but going up hills is when I notice it the most because it will stay in the low rpm high hear / overdrive even when pushing the pedal down and losing speed. When I take my foot off the pedal and back on the truck will always go to around 3k rpm and stay there for a second or two before the upshift sequence begins. Let me know what you guys think!

Replaced the tranny with a rebuilt.
Trans filter
Throttle position sensor
Spark plugs
Wire
Fuel pump
Fuel filter
Transmission fluid
Among other things. I am at the point where I'm throwing parts at it.