Help!! Is this a Knoll credenza?!?  

It doesn't look like Knoll to me, based on the recessed pulls and three-place cabinet with four leg base.  Looks more like Stow & Davis, though many companies made credenzas in this style, including Baker, Directional, Founders, Probber,  and more. 

It doesn't have recessed pulls. They are all missing. There are screw holes and cut outs for flat pulls. I agree about the base. Could it have been at on a different frame?

It is not Knoll but looks like by Stow Davis as mark737 mentioned. 

Find replacement look alike pulls & replace the top with white cararra marble if you like to get the Knoll look.  The top bar on the Knoll credenza are also square polished steel stock not like yours which is flat.

Here's a Stow & Davis credenza that looks like it could have the same pulls as OP's.  And with a marble top for the Knoll look as Minimoma suggested.   

Thank you so much for all of your help!!!!

Any suggestions on where I could sell it in the Houston area?

Stow and Davis made quality products but apart from some of their designer stuff, like the M.F. Harty pieces, their furniture doesn't sell for Knoll or Herman Miller prices.  Assuming the top is in good condition and you can find pulls, you might be able to get as much as $500 in a big city like Houston.  Facebook and Craigslist are your best bets for something like this.