Shifting Issue

I put up a post awhile back about my cars shifting issue but I've kinda recognized it a little bit better now. If I stomp on it (or push down gas pedal even hard at all) my car stays in 1st gear and won't shift into second and stays at around 4500RPM's and wont shift unless I let off the gas a bit and then put it back down. I checked transmission fluid and my oil is good so i'm wondering if my transimssion is going out? I'm having it looked at Monday but i'm wondering if any of you have ever had a problem like this so i can maybe know ahead of time. My car seems fine after II let off gas a bit and let it shift but it really ruins the fun in driving my car cause it will not shift on its own unless I let off or drive cautionsally and somewhat slow...(which i dont like doing). Could this actually be my transmission going bad?

When did it start occurring?
You running stock wheels still?
You can adjust that in the PCM with a Tuner, but if you haven't done anything major to through it off, then you have some tranny issue going on there.

It started occuring maybe 3 months ago and ive just been ignoring it but it seems to be really evident latley. I'm still running stock wheels and havent touched my PCM except to mount it on the heat resistant sheild on the K&N cold air intake mount and made sure connections are secure.

a guy that lives by me has a jeep wrangler that does the same problem .. for the most part its a problem with the tranny somewhere ... maybe try a shift kit idk if that would help also how is your fluid leval and what is the color of the fluid?