In sum, New Keynesian models are most certainly not reincarnations of textbook IS–LM models with maximization added on. Rather, they are real business cycle models augmented with a few distortions—typically sticky prices and monopoly power—and shocks that do little to contribute to fluctuations or influence the nature of optimal policy
From Kehoe, Patrick J., Virgiliu Midrigan, and Elena Pastorino. 2018. “Evolution of Modern Business Cycle Models: Accounting for the Great Recession.” Journal of Economic Perspectives, 32 (3): 141-66.
From http://www.tomsargent.com/research/romers3.pdf Reactions to the Berkeley story Thomas J. Sargent October 21, 2002
From James Heckman’s notes on Becker