1995 Chevy Astro stalling and sulfur or acid smell

Took my 95 astro van to szhop due to hard starting and stalling at stops, changed fuel filter. Better, but still not fixed. Now mechanic says fuel injector regulator is cracked, on this model, the injectors and assembly is ALL 1 piece, replaced injector and regulator assembly, still sputters and or dies at stops or slowing down. There is a sulfur smell, or like battery acid and a faint rattle noise. I am quadriplegic and need van for trips to UCLA for medical specialists, can't afford any more mechanic "trials" can someone help diagnose this? After sitting a day o r more, it usually starts right up and will run fine for a short while, then will start to sputter or die when stopped, what could this be? Also the sulfur smell? Thank you for your help. Desperate in CA