It is not unusual after you do a sucessful port job on an engine that you increased the fuel flow into the motor making it run slightly richer, so you need to retune the engine, a little bit leaner. After you have retune the motor it should be super responsive, unless you have really messed up the mod. As far as modifying your engine yourself don't do it if you can't afford to waste several piston & sleeves while you are developing skills with your dremel, leave the modifying to the pro's.