Acrid?? Burns the eyes?? My first thought is bad gasoline. These days you can get rotten gas right from the pump depending on how "kept up" the gas station tanks are. Since it's Springtime you may be burning gas from last year. The gas may be starting to turn. I would run her dry, completely empty and see how she does with fresh gasoline. If the tank has age on it ; it does have to be that old, you may have a blob of rotten gas in there. That stuff looks like tar and it will contaminate any new gas. I would run it empty and see how it does with fresh gas. If it still does it, I would try to check the tank to see you you have any tar/varnish/rotten gas in there.