Was he still writing comic books when he died?

Some of his colleagues (e.g. Jack Kirby, Steve Ditko) said he didn't write them even back in the '60s when he was getting writing credit. The "Marvel method" was for the artist to take an idea or outline, draw all the pages, and essentially write the story in so doing. Then, it would be sent to Stan Lee and he would put in the dialogue, based on the artist's notes in the margins. Kirby and Ditko both went on record saying Lee essentially wrote nothing himself. Giving possible credence to this is the fact that nothing Stan wrote after they left Marvel ever really gained any traction.

Lee was primarily editor at Marvel, and he was editor in chief up to 1972, after which he became publisher and was largely out of the creative side altogether. Then in 1980 he moved to L.A. and worked for years to get Marvel properties developed as movies and TV series, mostly without much success. Ironically, by the time Marvel did start to crack the movie business successfully (starting with "Blade" in '98), Lee had virtually no connection remaining with Marvel -- Marvel had offered him a 2 year contract for $500K a year (much less than he'd been getting) and no guarantee of a job past that 2 yrs. So Lee left and formed Stan Lee Media. That company, and his second one POW! Entertainment both failed to develop any projects successfully and disintegrated in bankruptcy and fraud claims, though Lee was cleared of any wrongdoing.

Lee, while at SLM and POW! did float some ideas for new characters and properties, but did little to no detail work himself, and none of these projects were successful.