intermittent no shift from 1st to 2nd

[dean1997sport]

This morning I was coming home from the bank and I take off from a red light and my transmission wont shift from 1st to 2nd went all the way to 3500 RPMS and then I let off the throttle it went down to around 2100 and it shifted. Got to the next red light took off same thing (light throttle not wide open). Both times flat surface no up or down hill grade. I did have the AC on so I turned it off at the next light and it did not happen again all day (with the AC on or off). My wife was in the truck with me at the time and she said it happened to her once before.

Any ideas why this is happening?

1997 sport 2WD 5R55E (i believe)

 

[BrooklynBay]

Adjust the bands, and check the fluid level.

 

[dean1997sport]

I cant seem to get a good reading form the dipstick? every time i try its just all over the whole bottom of the stick is there a trick to getting the correct reading?

 

[BrooklynBay]

Are you checking the stick with the engine running, and the vehicle sitting on level ground?

 

[dean1997sport]

Yes warm with the engine running i go through each gear and back to "P" and leave the engine running and there seems to be ATF in the fill tube and its all over the dip stick at random points. how hot does it have to be to check it? the best reading i have got was about a quarter of an inch above full but i dont think thats correct. is it possible to check it cold? and do i have to go through all the gears and leave the engine running if i check it cold?