1995 Chevy Astro bad smell

When the engine is cold and running rough it stinks of petrol but at running temp it smells of rotten eggs no mil light removed upper manifold to check regulator not leaking all ok no fuel leaks anywhere in or outside engine all sensors in tolerance replaced fuel pump, fuel filter, plugs, leads, distcap, rotor, tps, and it runs ok for a while then runs rough and stalls any help would be very appreciated mark