Default 02 Legacy Misfire/hesitation from Perfect Power 6?

[subaru_terrence]

First of all, i have a 2002 Legacy 2.5 NA 4EAT with headers, CAI, axleback, pulleys and perfect power street tuned for 91 octane.

Lets start off with my problems.
I used to have an old map with perfect power that was custom tuned for my car for 87 octane with just the intake. The car ran fine with it until I put in 91 octane.... it would have a knock/stutter at 70km/h around 1800rpm specifically. It was quite noticeable too. However, I dont recall i had that problem if i filled up with 87 octane.

After a year, I got it tuned again for 91 octane with headers and other stuff.
This is where the real problems begin:
let say if I do a hard pull in 2nd gear, I could feel the car hesitates and doesnt accelerate smoothly. When the rpm pass 5000 rpm, sometimes I can hear "misfire sound?" It sounds like "bap bap bap bap"

Also, if i just cruise around or drive smoothly in D, around 70km/h at about 1800rpm and if i step on the gas pedal half way through in D (without shifting down) when I am going 100+ km/h, the car would stutter too. :S

I hope you guys can understand my explanation of my issues and help me to solve my problems.
I recently changed the plugs and wires but the stutter is still there...

By the way, I dont have any CEL at all.

[anothernord]

Could potentially be a grounding issue for the trans. Check your main grounds around the engine bay for corrosion, rust, etc. If you have another tune map saved you could try to switch to it and see if its the tune that is causing it.

[subaru_terrence]

i guess i will try to check the groundings for the perfect power and around the engine bay when I have more time.

I also tried to switch around the maps. With the 91 tuned map, the hesitation is much more noticeable than my other 87 map but both maps have hesitation around 70km/h.