Dietbudda

HELP. I need it REAL bad right now. We just swapped a 3rd stage street ported, rebuilt 12A engine in my car. And so, we get it in, get it started up and it's all fine and dandy. We had to set it to idol at 1500 rpms. So here is my first question. Why is it needing that? Ok, so now i'm driving it around, breaking the engine in keeping the revs below 5 grand, varying speeds and such and then tonight, i'm driving around, had the car idoling a little bit and i get back on the road, the engine starts having problems plling at around 2 grand to 4 grand. I stop listening to my music and i can hear a rattling sort of noise from under the hood. So i stop, look inside the hood and everything is on tight, connected up in the right spot and seems normal. So i get my friend to rev it to 3 grand. I don't hear the rattle. So i get back in and i hear it agian. It tarts rattleing everytime the car is under load. So finally, i get home with 220 miles on the engine. and turn it off. Being as curious as i am, i try starting it up agian. no dice. It won't crank fast enough. finally, after about 3 trys and using the chock the car starts up. The car is well warmed up, so why would i need the chock? Ok, now the engine starts up and it's idoling at 1500 for about 20 mintues, then i turn the car off and i hear a real weird noise, cit's almost impossible to describe. Please help, i have no idea why this is so difficult. Everything is hooked up right, it's got fresh oil in it, it started up fine all day today. Any help is more then appreciated, thanx in advance.