Fired in Texas

What is the name of your state? Texas

I have been working as a contractor for the US Army. The company that hired me told me my position was as a Computer Specialist.
I have been doing mostly Instructional System Design work. After almost 2 months; I was called into the hiring managers office and told that I was being fired and given a week and 2 days notice. Reasons were for non-performance. I was told that I was hired as a Senior Programmer and being let go for not producing.

I been doing my work and meeting my deadlines. The on site manager has never express any dissatisfaction with my work. My contract calls for a Computer Specialist and it states that I should give and be given 2 weeks notice.

What can I do if I'm being fired without cause and under false pretenses?

My main concern is that the letter says that the reasons for my dismissal are:

1. Failing to produce as a Senior Programmer.
2- Misrepresentation of skill sets on resume.

I never accepted a position as a Senior Programmer and never listed that skill set on my resume. If I put down this job on my resume. What can they say my reason for leaving was?

Not much. Texas is an at-will state, and performance is in the eye of the beholder. Because you think your work is satisfactory doesn't mean your employer shares your opinion. Although it would have been nice to give you notice that they were dissatisfied with your work, the fact that they did not do so, does not make the reason false. Or illegal.

If you have a contract that states two weeks notice on both sides, you MIGHT be able to hold them to that. Otherwise, your recourse is to start looking for another job.