4-Spd w/Overdrive

Culd someone explain this to me, does this mean that the transmission will shift 4 times before dropping into overdrive? If so that must explain what I have been experiencing in my new 2007 F-150 with the 5.4-liter engine and 3.73 gears. If not please read below and give me your ideas.

Transmission changes from 1st to 2nd with no problems at all, the problem or at least what I think is a problem happens when the transmission changes from third to overdrive. Transmission seems to slip in and and of third gear just before it drops into OD at 2000 rpms. Almost seems like it is a five-speed transmission. Also I have a slight hesitation right at 2000 rpms when this happens.

Any ideas? Is this something I should be concerned about?

Thanks for your advice in advance.

 

It has 4 speeds including the OD plus the lock up of the torque converter. Acts like 5 speeds, but is really 4. After going to OD, it will lock the TC. You can easily tell when it is locked, if you have a tach. When locked, and you give it light gas the tach will only climb as speed climbs. If in OD and TC unlocked, the tach will move up and down with the amount of gas you give.
If you give it gas hile in OD and the TC is locked, and it needs to downshift, the first thing you will feel is the TC unlocking, then an downshift to 3rd.

 

Thanks kingfish51 for helping me understand how this transmission works.