X Misfiring and shaking in reverse when cold.

[boomer89]

I have a 2001 4.4i X5 its got like 200.xxx km on it. I already did a post on the misfiring did not get much back but I am going to try again because this is just driving me insane. I took the X to the stealers with a check engine light and they told me it had misfiring coeds on all 4 cylinders on one side but they did not know why it was doing that. Then they tell me that they thoghut it was false air coming in to the engine or something but where not sure. I can feel the X shaking when i put it in reverse when its cold but not when warmead up it also misfires alot when it is warming up. Than when I am cruising at about 90km and accelerate it also misfires also when I am coming to a stop at a light and it turns green before I stop and I accelerate it misfires. Some solutions to this would be much appreciated thanks.