power FC with Z32 MAF question

[sli240sx]

Whats up guys, i just have a question on the Power FC. I have a sr20det with a Power FC and a Z32 maf. I had it tuned at a shop which made 415whp and 360 torque. The tuner told me that the tune I had was with the original SR MAF and it would take much longer if I wanted to switch it over to the Z. Would that be a problem or is it the same as the Z32 one? I know the Z one can hold higher horsepower cause it reads a lower reading but would that mess up the driveablity of the car? Right now I have a little problem when I'm crusing around 2500 rpm. The car starts to studder a little. This only happens when I'm drive. I was also thinking i could be the coilpacks, they are pretty old. Is there a way to test the coilpack to see if they are working correctly? Or if anyone has another idea why its doing that...

[sli240sx]

i for got to mention that I did change my plugs to NGK IR plugs one step colder. gapped at .030.