i've been driving my mom's 03 Yukon the last few days since she's been home off work all week. she had complained about it "acting weird" in the past but i didn't think much of it. well, i drove it to school monday and at part throttle accel. it flutters almost, kinda like if you've ever ran out of gas, and at cruising speed on the highway if you nail it to pass it doesn't down shift as fast as it should (or as fast as mine does) anyone had any of these problems with an 03? i thought it might have something to do with the fly by wire.