Hello sir!

 We have this ford everest 2005 first generation, Automatic transmission running on it 200,000 mileage, we experienced that when you put it on (D) drive it takes time to move forward like it has no power at all the RPM will not even reach 2000, specially if it is in upward road the car wont even move already , but when it is in flat surface it can move but need to wait for a certain time before it reach 2000 rpm, when it already reach 2000 rpm the car will now run normal it will shift like it is normal , tried to go to calibration center have my injection pump tested and it is all good , Also changed my air filter , fuel filter,   also did changed the ATF of it .  What seems to be the problem here sir?

Thanka you