Okay so I have a 1990 z32 N/A. I installed a set of Z1 headers on the car last week. When I picked it up from the shop I noticed a slight hesitation under acceleration . Everything else is fine just under power does it do this. I have researched everywhere online and find so much that could be the problem. Could the shop have messed something up? Vaccum line? O2 sensor damaged? I noticed that they removed the brake master cylender during the job and unplugged many vac lines. I have checked all of them and they seem fine. Could running the headers cause the car to run this way? Any help you may offer would be greatly appreciated. Thanks, Bill