Box SDK with node.js

I have an application which when scaled up seems to hang on node.js

The application takes a list of files from a csv and then checks if the folder exists and creates if required. 

Then it uploads the file to the folder and sets collaboration on the file.

With 5 or even 30 files there seems to be no problems but when this is raised to 500 for the production test it reads the CSV but then seems to hang and does nothing else.

Below is the code used for this process. 

Does anyone know why this is causing a problem ?

As there are no errors thrown and I cannot see what box is receiving its hard to tell if its the client (node) side or box where the issue is occuring

var stream = fs.createReadStream(inputFilePath);
csv
.fromStream(stream, {headers : true})
.on("data", function(data){
// return new Promise((resolve,reject)=>{
try {
console.log('Row: ' + i);
i = i + 1;
//res.send(data);
// Set folder values
var nFolderId = '';
// Does Folder Exist - Test on Box
foundfolder(data.EMAIL,folderId,client).then((nFolderId) => {
console.log('Found ?: ' + nFolderId);
if ( nFolderId == '0' ) {

client.folders.create(folderId, data.EMAIL).then( folder => {
console.log('New Folder :' + folder.id) ;
var stream = fs.createReadStream(data.FILEFROM);
client.files.uploadFile(folder.id, data.FILETO, stream, function(err, items) {
if (err) {
console.log("Failed Write :" + data.FILETO);
} else {
console.log("Success Writen :" + data.FILETO);
client.collaborations.createWithUserEmail(data.EMAIL, folder.id, client.collaborationRoles.VIEWER, function(err, items) {
if (err) {
console.log("Failed Collab :" + data.EMAIL);
} else {
console.log("Success Collab :" + data.EMAIL);
}
})
}
});

});
} else {
console.log( 'Existing Folder:' + nFolderId);
var stream = fs.createReadStream(data.FILEFROM);

client.files.uploadFile(nFolderId, data.FILETO, stream, function(err, items) {
if (err) {
console.log("Failed Write :" + data.FILETO);
} else {
console.log("Success Writen :" + data.FILETO);
foundcollab(data.EMAIL,folderId,client).then((nFolderId) => {
console.log('Found ?: ' + nFolderId);
if ( nFolderId !== '0' ) {
client.collaborations.delete(data.EMAIL, folder.id, client.collaborationRoles.VIEWER, function(err, items) {
if (err) {
console.log("Failed Collab :" + data.EMAIL);
} else {
console.log("Success Collab :" + data.EMAIL);
}
})
}
})
client.collaborations.createWithUserEmail(data.EMAIL, nFolderId, client.collaborationRoles.VIEWER, function(err, items) {
if (err) {
console.log("Failed Collab :" + data.EMAIL);
} else {
console.log("Success Collab :" + data.EMAIL);
}
});
}
});

}
})
// } // end promise
}
catch(err) {
console.log('err found' );
}
})
.on('end',function(){
//some final operation
});

The folder check is carried out by this code

function foundfolder(fname,folderId,client) {

return new Promise(function(resolve,reject) {
console.log(fname);
var nFolderId = '0';
var foundfolder = 'False';
client.folders.getItems(folderId, null, function(err, items) {
if (err) {
reject(err);
} else {
items.entries.forEach(function(element) {
if ( element.name == fname ) {
nFolderId = element.id;
};
}, this);
resolve(nFolderId);
}
})
})

Thanks for any pointers.