[statik]

If there is NO change what so ever and the car sounds like its not running on all cylinders, make sure 2 and 3 are getting fuel/spark. Pull the coil out and see if it conducts on the intake mani. You can hear if the injectors are firing by placing a screw driver tip on the injector seat and placing the handle to your ear. Chances are since you didnt touch wiring all the injectors are firing. Did you do anything other than swap the rail directly to the new manifold? Last thing that can make it seem like 2 and 3 aren't firing is a lack of compression, i.e. blew the head gasket between 2 and 3. Since you did the HG im leaning towards that more than anything else. What gasket did you use? Start with a compression test.