When I accelerate from about 2300 rpm in 2nd or 3rd gear I get a spinning/ rattling noise from somewhere around the right side of my engine ( drivers perspective) . Its not until I'm well in gear before the noise happens, not so much while I'm shifting. This does not happen in 1st gear either. The noise stops as soon as I left off the gas and doesn't always comeback, until I have to upshift again. The best way to describe the noise is like something loose is spinning freely without being attached properly. Not sure what it could be has anyone experienced this before ?

95 3.4 v6 thanks

 

My car has been doing this for awhile. Mine turned out to be the heat shield for the catalytic converter. It does it at 2250 RPM's up until like 3000 RPM's. Try smacking the heat shield real hard and see if it makes a familiar sounding "spinning" noise