Hi J.,
I have not seen what this particulalar stroller looks like, but I have had the same problem with other strollers. The best thing I have found to do, after doing all that you have done, is to take it apart. Most strollers have snaps on the fabric parts and the covers can be removed. Airing it out and Frebreezing it just wont cut it. Some strollers are real easy to do, and others take a little more work. I actually had to unscrew the material on a Graco stroller to get the cover off, but after I did that, and soaked it to get the dirt and smell off, and scrubbed it, it was worth it. It looked brand new. I didn't put it in the washer, just because I didn't want the padding to shift. If you need to, take upclose pictures of how it is put together so that when you take it apart, you can reassemble it. Maybe someone else has a better idea, but I know this worked for me. Good Luck!