diff --git a/actionpack/lib/action_controller/request.rb b/actionpack/lib/action_controller/request.rb
index 5e492e3..8c50874 100755
--- a/actionpack/lib/action_controller/request.rb
+++ b/actionpack/lib/action_controller/request.rb
@@ -492,10 +492,13 @@ EOM
 
         case strategy
           when Proc
-            strategy.call(body)
+            if strategy.arity == 4
+              strategy.call(body, boundary, content_length, env)
+            else
+              strategy.call(body)
+            end
           when :url_encoded_form
-            self.class.clean_up_ajax_request_body! body
-            self.class.parse_query_parameters(body)
+            self.class.parse_url_encoded_form_parameters(body)
           when :multipart_form
             self.class.parse_multipart_form_parameters(body, boundary, content_length, env)
           when :xml_simple, :xml_node
@@ -528,6 +531,10 @@ EOM
 
     class << self
       def parse_query_parameters(query_string)
+        parse_query_parameters_with_parser(UrlEncodedPairParser, query_string)
+      end
+
+      def parse_query_parameters_with_parser(parser_class, query_string)
         return {} if query_string.blank?
 
         pairs = query_string.split('&').collect do |chunk|
@@ -538,11 +545,24 @@ EOM
           [ CGI.unescape(key), value ]
         end.compact
 
-        UrlEncodedPairParser.new(pairs).result
+        parser_class.new(pairs).result
+      end
+
+      def parse_url_encoded_form_parameters(query_string)
+        parse_url_encoded_form_parameters_with_parser(UrlEncodedPairParser, query_string)
+      end
+
+      def parse_url_encoded_form_parameters_with_parser(parser_class, query_string)
+        clean_up_ajax_request_body! query_string
+        parse_query_parameters_with_parser(parser_class, query_string)
       end
 
       def parse_request_parameters(params)
-        parser = UrlEncodedPairParser.new
+        parse_request_parameters_with_parser(UrlEncodedPairParser, params)
+      end
+
+      def parse_request_parameters_with_parser(parser_class, params)
+        parser = parser_class.new
 
         params = params.dup
         until params.empty?
@@ -567,7 +587,13 @@ EOM
       end
 
       def parse_multipart_form_parameters(body, boundary, body_size, env)
-        parse_request_parameters(read_multipart(body, boundary, body_size, env))
+        parser_class = UrlEncodedPairParser
+        parse_multipart_form_parameters_with_parser(parser_class, body, boundary, body_size, env)
+      end
+
+      def parse_multipart_form_parameters_with_parser(parser_class, body, boundary, body_size, env)
+        params = read_multipart(body, boundary, body_size, env)
+        parse_request_parameters_with_parser(parser_class, params)
       end
 
       def extract_multipart_boundary(content_type_with_parameters)