lack of power/ dtc #27

i just finished installing a pacesetter header and port/polished the head on my 92 4.0l. I should probably add that my old manifold was cracked so bad that it was misfiring for about a week and a half. after that work, my xj feels like it is lacking a lot of highway torque that it had before. twice while going up hill just after shifting into fourth gear it started to shudder and set the check engine light. i checked the codes and got a #27-injector circuit. any ideas?

Did you pull the fuel rail and injectors from the intake manifold, or leave it attached?

i left it all attatched to the intake and set it asside under the work bench.