Ha, I agree most of his books evoke having been written during stimulant binges; rich and detailed world building in the beginnings transition to incoherent plot driven action at the endings
Possibly The Baroque Cycle though it's been a while since I'd re-read it.
His political fiction (Interface and The Cobweb) were also fairly traditional, though he had a co-author on those.
Anathem had perhaps the biggest deux ex machina in literary history, and seveneves had an entirely separate novella for an ending.
Seveneves had a conclusion, and then an extra book...