i am having a big problem since i replaced my intake gaskets 3 weeks it ran really good then all of a sudden i get missfire cyl 3 and injector driver circuit.i have replaced coil.wire spark plug,and checked injector it is spraying. everytime i clear the code 2 seconds later both codes come back. what do i check now? i was thinking computer and can i get a junk yard unit and swap them out without reprogramming?

I would move the injector to another cylinder, clear the codes and try again. If you get the same error but on the new cylinder, then replace the injector. The injector can spray, but still be bad because it does not fully shut off when signaled to do so, or does not indicate to the injector driver circuit that it has closed.

Have you checked MAF sensor

no i didnt clean the maf i have a k&n filter on there too. but will that injector not closing fully make the car run like it is on 5 cyl missing at idle and hesitaing when you press the throttle. the plug is clean on that cyl too.

Check the car for vacuum leaks. This is a common cause for misfires.

this is todays update i started the car up this morning car drove fine all day. i didnt shut it off then i turned it off for about 20 mins and came back. check engine light was back and i was getting cyl 3 missfire and injector control circuit codes again. car would hesitate on acceleration then i pulled over with car still running cleared codes car was back to normal again. smooth like it was earlier if i let car sit when engine temp is over 200 for about 20 mins car will restart with 2 codes every time if i start it up and shut it off right away no codes. my next day off i will be replacing injector, i swapped out maf off my regal gs and i was still getting the same issues.

See if you can hear the injector when it'* missing. How does it sound? Check the wires and make sure nothing is loose or grounding.