When I start my car it runs very loudly, and seems to have trouble to stay running when I pull up to a stop. Also it kind of jumps when it shifts into 2nd when I first hit the road.When I try to back up and drive to work the rmp goes down to about 500rpm in reverse and will almost certainly stall when I put the car back in drive to head to work. Could it just be a loose belt? O2 sensor? Any help would be greatly appreciated! thanks

 

Year, model & mileage would be helpful. SES light on? If so, have the code(s) pulled at any auto store for free.

 

Have you done a visual inspection?
Have you lifted the hood and listened for where the sound is coming from?

A few more clues would go a long way toward figuring this out.

 

2000 maxima SE, 233k km, no lights are on. What are these codes you speak of?

 

I just checked under the hood and it seems as if the sound is coming from the belts or the left side of the engine. Would having a loose belt cause my car to stall?

 

A loose belt will usually give a high pitched squeal. Bad pulleys will cause rattles or vibrations. Neither should cause stalling like you're describing. If it stalls from a belt issue it wont start again.

Can you describe the sound better?

 

Best way to describe it is that it's a rattling from inside the engine, I hear high pitch squealing when I turn a corner at times. Also sometimes when I start my car other than the rattling, I'll hear what sounds almost like a pump being activated from the glove box.

 

Might be helpful if you take a video of the engine with the sound and upload it to Youtube. That should give the guys here something to work off of.