Johnsson, Sven and Petersson, Ida

[Bart Emanuel]

I am looking for the origins in Sweden of my wife's great grandparents.  Unfortunately, I don't know what parish (or even county) in Sweden they are from.  They are listed in the 1900 census of Torrington, Litchfield county Connecticut as:
Swan L Johnson, born 15 October 1860, immigrated to USA in 1882.
Ida Johnson, born 15 November 1870, immigrated to USA in 1888.
 
I started to go through the microfilms for New York arrivals for those years.  Unfortunately, there is no index for this period, and there are many, many ships.
 
Also, I do not know if the names were americanized.  I realize that there are variants of Sven/Svan/Svend and Johnsson/Jonsson/Johansson etc.  I also do not know if Ida used her patronymic or surname, but my wife's father says that it was Peterson.
 
If I could get some candidates for these dates of birth and emigration from Sweden, I can start researching the parish records.
 
Sven and Ida had three children, all born in the USA:  Albert, born 1/1892 in Connecticut, Arvid, born 2/1894 in Connecticut, and Hjalmar, born 8/1895 in Massachusetts.  The family moved to East Longmeadow, Massachusetts before 1920 and settled there.  
 
Arvid, my wife's grandfather married a nice Norwegian girl from Krager?, Telemark.  I have been able to trace her tree via the Norwegian census and microfilmed church records.  She also has Swedish ancestors who moved from Vännäs sok in Västerbottens län to Krager?!  (Johan Matsson b. ca. 1829, and Anna Magdalena Carlsdotter, b. ca. 1832).