You didn't mention what style/type of water you have so will address the common one - the suburban dual gas/electric. Did you fill your water tank after taking out of storage and if so, where? Were you on city water in Cody? As you mentioned replacing the plug in the heater I will assume you had an empty heater while in storage so...
First, inspect and replace if necessary the anode. Sometimes this is also the electrical heating element in the heater. The smell can be caused by out-gassing of the calcification being burned off. We noticed an increase in calcification while in Texas due to the hard water so paid attention to the quality and used a softener in several areas.
Cody has naturally sulfur smelling water and a good charcoal filter is highly recommended if you are using city water. This is true anywhere in the vicinity of Yellowstone - nature of the beast being in/one a volcano.
You may have sediment in your heater tank that no amount of changing anodes or heating elements will cure. A thorough flush-out while dewinterizing or after taking out following an extended storage is highly recommended.
Lastly, white vinegar is your friend and there are several videos out there covering its use in a water heater to clean it out.