too_many_requests when uploading multiple files

Thanks so much for your help. How would I go about only uploading one file after the callback has completed? This is my code:

function uploadFiles ( storageFilePaths, packFilePaths, packRoot ) {
	for (i in storageFilePaths) {
		dbx.filesUpload({ path: packRoot+packFilePaths[i], contents: fs.readFileSync(storageFilePaths[i]) })
			.then(function (response) {
				console.log(response);
			})
			.catch(function (err) {
				console.log(err);
			});
	}
}