Hesitation at high rpm/under boost p0302 and p0171

Hi, I have a 2003.5 mazdaspeed protg. It is mostly all stock except for upgraded plugs, wires, and a k&n filter in the stock intake box. The car has 190xxxkm on it. I have been experiencing hesitation mostly after 4000rpm or when hitting boost. The car also only does this after it has been warmed up. I have replaced, spark plugs, spark plug wires, both ignition coils, and I have seafoamed the intake, and used a seafoam cleaner into the gas tank and a bit into the oil. The car reads on an OBDII scanner p0302 (cylinder 2 misfire) and a p0171(Lean) If anyone could help that would be great.

Are the plugs gapped correctly? You will get hesitation under boost if they are not and it is an easy fix. They need to be gapped to .028-.032" and most come >.04". I don't know if that will cause a misfire code like that, but it's possible.

I had a persistent p0171 for a while that was caused by a loose exhaust manifold. I guess over time the screws can work their way out of the head. Tighten them back down to the correct torque (it's easy to strip them if you aren't careful!) and it will most likely go away. It is a "lean" code because some of the exhaust gas is escaping at the manifold above the O2 sensor, so the sensor is getting a bad reading.

I agree double check the plug gap, especially if the coilpacks AND wires are new. Lean code is from a vacuum leak, could be from a gasket leak, vacuum line, ruptured wastegate actuator diaphragm, failing/dirty O2 or MAF, EGR, cracked exhaust manifold, etc.

Thanks for the help, took the heat shield off of the manifold and discovered a large crack going almost all the way around between the 2nd and 3rd exhaust runners. Ive heard what sounded as an exhaust leak but have never smog tested where the leak may be. I will also check the gap of the spark plugs and re-gap if necessary. Thanks for the help once again!