Ok my 94 has had an occasional rotten egg smell for the past month. This happens usually on hot days. Well finally today it threw the 1131. Before all this the plugs and wires changed, maf cleaned, fuel filter changed, sea foamed. Bought the car with 112k on the clock (broken odometer now replaced) and have put 4k on it since. Best place to start? Injectors, o2's or cats themselves? Do not know car history.