Hi All,

I am having a problem I am not sure how to diagnose and the car throws no codes.

Car is a 2003 e53 4.4i with 150K miles. Spark-plugs replaced at 100k, transmission was rebuilt around 60K miles, motor mounts replace recently.

I dont know if it is the engine, transmission, guibo, or something else.

When I am accelerating uphill at about 2.5K RPMs the car starts shuttering but if I go above 2.5K RPMs the shuttering smooths out. If I just held it at 2.5K RPMs uphill it would continue to shutter. It doesn't happen all the time but seems to only occur going uphill. I also notice an intermittent higher pitched whine at higher speed on the freeway that seems to come on and off when i press the gas pedal though it is not a very loud whine and I dont know if these problems have anything to do with each other.

I dont know what this could be. I have had bad coils before and it felt similar but I was eventually getting codes. I dont have anything to go on this time.

Any thoughts or suggestions or other things to check?

Thanks!