Two sources you might consult are Gabriel Kolko’s book, The Limits of Power: The World and United States Foreign Policy 1945-54 and Michael Cox’s article, “The Tragedy of American Diplomacy? Rethinking the Marshall Plan,” Journal of Cold War Studies 1 (2005), pp. 97-134.
Here are two pieces that cite Cox and Kolko:
http://www.sscnet.ucla.edu/polisci/faculty/trachtenberg/cv/jcws%28marshall%20plan%29.pdf
http://nevinpower.weebly.com/uploads/6/0/5/3/6053998/the_marshall_plan_-_the_extension_of_empire.pdf
