Transmission Issue? Sensor..

[infi30t]

This is my first post, but I am active on other forums with multiple other cars.
I have done searching through this forum and have found nothing describing what I have going on here...This is my Great grandma's I30t and something is wrong with it. I picked it up from her today and she was complaining that there is no power. She said when she puts her foot in it to go or get around someone, it doesn't do anything. So I took it and i put "my foot into it" as she was saying as im driving at about 40mph and she is correct. I can floor it and it just sits there and revs to about 4-4500k rpms. And it will barely move. Now I can feel it downshift before it does this so... After driving it for a bit it seems to happen at about 3/4 throttle and up. Other than that it shifts perfect (occasional hard shift here or there) and as long as its under 3/4 throttle its fine. But I don't want her to get into a bind and have to use a little more power than normal and not have it there for her. What this sounds like to me is some kind of sensor. Does this sound right? Drives fine normally, but any hard acceleration it gives out. What do you guys think this could be. I am fairly mechanically inclined so shoot away!
Thanks in advance!

 

[infi30t]

So I took the car to a local transmission guy that is quite reputable and he said the transmission is doing its thing correctly. He said it is hitting the rev limiter. In park it does not hit the rev limiter, it revs all the way to red line. But when driving and I floor it, it will only rev up to 4500 and just hold there... Any ideas????

 

[Mdominosr1]

Feels like my car is doing the same thing