My transmission won't down shift when I mat the gas pedal to the floor, it will only stay in one gear the whole time, and it'll reach like 5500 rpm and will climb so I lay off the throttle, it won't shift into a higher gear. Please help, I need to know what to do.

 

Can you manually shift it? What gear is it stuck in? Have you checked the TV cable for being stuck, broken or disconnected. Does it start in 1st and shift up to 4th rapidly? Have you recorded line pressure yet? We need a lot more info to help, BUT be VERY AWARE that a malfunctioning TV cable/valve will very rapidly destroy your transmission and force a rebuild if you drive it that way.
I rebuilt my transmission this summer, the TV valve stuck in the bore and after only two WOT attempts to force a downshift, I destroyed the 3-4 clutches and will be rebuilding it again his winter.
A stripped governor gear will also cause problems, but I've forgotten those exact symptoms.

 

I can manually shift 1st to 2nd and 3rd and 4th. But everything I'm in drive or od it will just stay in one gear. In drive it will shift 1st to 2nd within 10 mph. It seems that it has a very short 1st gear. But under wot it will not shift in drive or od. The only time it would shift at wot if I just pedaled it a few times, but it rarely shifts like that too.

 

The TV cable must be tight at WOT. If it is, then you need the TransGo non sticking Throttle Valve setup at a minimum. I carry this if needed. Take a pressure reading if this does not solve this.