protected function _oauthRequest($uri, $params, $getParams = array()) {
        if ($this->debug) { $start = microtime(true); }

        if (!isset($getParams['oauth_token']) && isset($params['oauth_token'])) {
            $getParams['oauth_token'] = $params['oauth_token'];
        }
        if (!isset($getParams['oauth_token'])) {
            $getParams['oauth_token'] = $this->getAccessToken();
        }
        // json_encode all params values that are not strings
        foreach ((array)$params as $key => $value) {
            if (!is_string($value)) {
                $params[$key] = json_encode($value);
            }
        }
        if ($this->debug) { $this->timer[__FUNCTION__]['elapsed'][] = microtime(true)-$start; }
        return $this->makeRequest($uri, $params, null, $getParams);
    }