Have been getting rotten egg smell for 3 weeks, stalling in neutral the same period and stalling in drive the last week. Codes showed air flow sensor and ecu ground wire faulty. Both replaced, however, voltage at the ecu remains at .9 volts when it should fluctuate between .2 and .9 during diagnostics. This creates a rich condition causing the rotten egg smell. Absolutely no other code have shown up. Any ideas? Thanks