I have a 03 maxima that is make this God awful rattling sound when I start accelerating if I let off the throttle it will stop or if I accelerate more it will stop and it also does it upon start up

 

Probably exhaust heat shields. I found one of mine floating, the holes were as big as the bolts that hold it on. I put some washers on it and it quieted it up. It was doing the same as yours.

 

Hell yeah man I'll try it their is only so long I can take that ****

 

possibly timing chain tensioner. i had a rattle at around 2k rpm, noticed it mostly going up hills. i would take my foot off the gas and it would stop. i had my tensioner replaced and switched to full synthetic oil to help clean the engine a bit more. the tensioner i believe works with oil pressure and the little hole that feeds it can get clogged.

i'm pretty new at all this stuff so take this for what it its. i know the tensioner is a common problem.

 

^Good point. The "on startup" part makes me think that it is a good possibility also.

 

Sound like detonation or a can of marbles?

That could also be the infamous precats...