I've had my check engine light on on my '01 A6 for a while and I feel a slight hesitstion when I try to accelerate, especially at low speeds or when I'm at a standstill and I step on the gas to go. If I press the gas with a little extra force its more noticable. I've been told it could be a sensor but I don't know because the hesitation is very constant. The only time I can step on the gas with confidence is on the highway at high speeds, because I could barely notice it. I wonder If anyone knows what this could be. I took it to a transmission specialist just to be safe, and he assured me it wasn't the transmission, so I need some help.