[TahoeM3]

Got my X5 back with new injectors and plugs. Everything seems back to normal...no rough idle, no long cranking, no black soot, and no check engine light. Power and gas mileage seem about the same...although it was no slouch before, being faster than a new S5 coupe off the line to around 80 when I let up, and door-to-door even with a Mustang GT 5.0 on a 40-100 roll.

While I was at the dealership, I drove an X5M and a new M5 (awesome, btw) and I can say the difference between the 3 is pretty subtle. I know the 50i is slower, but it's not a big difference...the difference among them is much less noticeable than the difference between any of them and my GTR, for comparison.

Whatever the case, all seems back to normal. For anyone else having these problems, it's definitely the injectors.