Hey Community

Im a new member and have turned to you experts for some advice. Im currently driving a 2005 G35 Sedan with approximately 142k miles. Lately I've noticed a slight pulling/lurching when shifting gears. Its definitely noticeable under moderate to heavy acceleration or going up hill, where it seems I'm low on power/sluggish. It will also drop revs down to idle then jump back up to whatever normal for the gear. If I'm at highway speeds, i can speed up smoothly with no problems. Infiniti checked the transmission and its throwing no codes and the fluid is clear/not burning. Infiniti suggested it might be the Throttle Body Assembly or similar however they couldn't give me a clear answer. Any ideas what it might be?