How's the condition of the fluids in the truck? All Hemis have coil-on-plug ignition so your rough idle may be attributed to a failing coil. My A6 is great, a whole lot of fun. It has Quattro AWD but it has a rear drive bias. I'm supercharging it in the summer. It's a tad bit heavy but it's great. The maintenance is a bit high, but that's normal with German cars.