2000 4.7 cold Trans

I have a 2000 4.7 (40k miles) with the Heavy duty cooling, When ever I take off with it cold It sounds like the Transmission is really slipping (although I think most the noise is from the clutch fan) and the RPM go quite high just to get it moving. I dont think the torqe converter locks when it should. within a block or so its fine. Its had the trans fluid and filter changed. any ideas? would a transmission output sensor control that

Thanks

Sometimes, after a tranny service, the tech will
install a filter # 04799662ab, or equivilant.
This filter can allow the toque convertor to drain back into the oil pan over a period of time (like overnight) this causes a slipping feeling in the morning.
You can get a proper filter from a Dodge dealer part number is the same but without the AB at the end.
04799662

yes thats what i was gonna suggest, my dakota has the same problem sometimes....after sitting all the fluid drains outta the converter and when u first go to move in the morning it acts a little sketchy, but usually never takes more than a few seconds to correct itself\