my 2003 Mercedes ML 350 makes squeaking sound when i try to accelerate, otherwise it run wells. What could be the problem?

What is your question?

My 2003 Mercedes ML 350 makes squeaking sound whenever I try to accelerate, otherwise it run wells. What could be the problem? This happens only when I step on the accelerator.

What makes this problem better or worse?

Same situation all the time. Not affected by any condition.

How long has your 2003 Mercedes-Benz ML350 had this problem?

A few weeks