OutOfMemoryException when reading a Json string

I am trying to deserialize Json data from a web feed that is ~1.7 GB in size. I started with the following code:

public override void CreateNewOutputRows()
{

    //Set Webservice URL
    string wUrl = "webserviceURLgoeshere";

    try
    {

        RootObject outPutResponse = GetWebServiceResult(wUrl);

        foreach (Impression imp in outPutResponse.impressions)
        {

            ImpressionsSheetOutputBuffer.AddRow();
            ImpressionsSheetOutputBuffer.token = imp.token;
            ImpressionsSheetOutputBuffer.userid = imp.userid;
            ImpressionsSheetOutputBuffer.itemid = imp.itemid;
            ImpressionsSheetOutputBuffer.view = imp.view;
            ImpressionsSheetOutputBuffer.imageguid = imp.imageguid;
            ImpressionsSheetOutputBuffer.bytes = imp.bytes;
            ImpressionsSheetOutputBuffer.format = imp.format;

            ImpressionIDBuffer.AddRow();
            ImpressionIDBuffer.oid = imp.imId.oid;

            ImpressionParamsBuffer.AddRow();
            ImpressionParamsBuffer.origformat = imp.imParams.origFormat;
            ImpressionParamsBuffer.size = imp.imParams.size;

            ImpressionTimeBuffer.AddRow();
            ImpressionTimeBuffer.numLong = Int32.Parse(imp.imTime.numLong);
        }
    }

    catch (Exception e)
    {
        FailComponent(e.ToString());
    }
}

private RootObject GetWebServiceResult(string wUrl)
{

    HttpWebRequest httpWReq = (HttpWebRequest)WebRequest.Create(wUrl);
    HttpWebResponse httpWResp = (HttpWebResponse)httpWReq.GetResponse();
    RootObject jsonResponse = null;

    try
    {

        if (httpWResp.StatusCode == HttpStatusCode.OK)
        {

            Stream responseStream = httpWResp.GetResponseStream();
            string jsonString = null;

            using (StreamReader reader = new StreamReader(responseStream))
            {
                jsonString = reader.ReadToEnd();
                reader.Close();
            }

            JavaScriptSerializer sr = new JavaScriptSerializer();
            jsonResponse = sr.Deserialize<RootObject>(jsonString);

        }

        else
        {
            FailComponent(httpWResp.StatusCode.ToString());

        }
    }

    catch (Exception e)
    {
        FailComponent(e.ToString());
    }
    return jsonResponse;
}

private void FailComponent(string errorMsg)
{
    bool fail = false;
    IDTSComponentMetaData100 compMetadata = this.ComponentMetaData;
    compMetadata.FireError(1, "Error Getting Data From Webservice!", errorMsg, "", 0, out fail);

}

}

public class Id {

    public string oid { get; set; }
}

public class Params {

    public string origFormat { get; set; }
    public string size { get; set; }
}

public class Time {

    public string numLong { get; set; }
}

public class Impression {

    public Id imId { get; set; }
    public string token { get; set; }
    public string userid { get; set; }
    public string itemid { get; set; }
    public string view { get; set; }
    public string imageguid { get; set; }
    public int bytes { get; set; }
    public string format { get; set; }
    public Params imParams { get; set; }
    public Time imTime { get; set; }
}

public class RootObject {
    public List<Impression> impressions { get; set; }
}

However, the StreamReader ReadToEnd method is where the exception gets thrown, as the size of the data is too large.

I tried changing that code to the following:

Stream responseStream = httpWResp.GetResponseStream();

StreamReader reader = new StreamReader(responseStream);

using (var myjson = new JsonTextReader(reader))
{
    JsonSerializer myserialization = new JsonSerializer();
    return (List<RootObject>)myserialization.Deserialize(myjson, typeof(List<RootObject>));
}

This gives me an error that I cannot implicitly convert type List<RootObject> to RootObject. Does anyone see what I might be doing wrong that I can't make this conversion? I used this question to get around the OutOfMemory exception, but now it returns no deserialized items. Any advice would be much appreciated.

EDIT: Json data looks like the following:

{
"_id": {
    "$oid": "000000000000000000000000"
    },
"token": "00000000-0000-0000-0000-000000000000",
"userId": "username",
"itemId": "00000000-0000-0000-0000-000000000000",
"view": "view1",
"imageguid": "00000000-0000-0000-0000-000000000000",
"bytes": 1000,
"format": "PNG",
"params": {
    "originalFormat": "tif",
    "size": "50x50"
    },
"time": {
    "$numberLong": "1458748200000"
    }
}
{
"_id": {
    "$oid": "100000000000000000000000"
     },
"token": "00000000-0000-0000-0000-000000000000",
"userId": "username",
"itemId": "00000000-0000-0000-0000-000000000000",
"view": "view1",
"imageguid": "00000000-0000-0000-0000-000000000000",
"bytes": 1000,
"format": "PNG",
"params": {
    "originalFormat": "tif",
    "size": "50x50"
    },
"time": {
    "$numberLong": "1458748200000"
    }
}