Well i just bought my tahoe today. I took it out for a test drive yesterday before i bought it. Anyways i got a really good deal that i why bought it. It run really bad. Under normal driving it is really smooth and runs great. As soon as i go full throttle it falls on it's face. It likre stubbles really bad and the rpms dont even go up and the studders really bad. It will not even shift. I got a check engine light and autozone said the code was po171 something with the mass air flow sensor. Can you guys please help me out. I already took off the K&N filter and cleaned it and the mass air flow sensor i am just wainting for it to dry and i will put it back on.