Okay so I'm more mechanically inclined then the average person been working on my own cars as long as I've been driving. But I never owned or worked on a stang before, still learning the in's and outs. My girlfriend drives a 03 gt vert that she purchased used with some after market bolt-on parts. I've identified only CAI, cat back, and trick flow throttle body so far while working on it. Not sure if there are other parts installed. Before we met and not long after owning the car she had something with the cooling fan fail and the car overheated and needed work. Not long after that she developed codes P0174 and P0171 (lean condition both banks) and a coolant leak in the intake. I replaced the intake manifold and gasket thinking it would fix the codes as well (made sense leaking intake would let in more air) But codes remain and I'm working on troubleshooting them. Biggest question I have for you is whether or not the bolt-on's listed above could allow enough extra air into the engine to throw these codes? If so a tune would fix this? I have a live data obd device on order so I can look at long term fuel trim and O2 voltages but I'm open to guidance from people smarter than I. Thank you!