dead spot at low RPM's

[bp]

I have a 1990 300z na 2+2 that I did a JDM motor swap. I put test pies on and took cats off. Do I need to do anything with the tubes that the 02 sensors were hooked up to? when traveling in second gear around 2000 RPM and I stomp the gas it seems there is a dead spot before it goes. if i do the same thing at 3500+ it runs strong. What could be causing the low end dead spot?? it idles around 900 RPM and pretty smooth. Once in a while when going thru the gears i can see a little hint of black smoke come out of exhaust between shifts (someone else driving). Also when I put the back exhaust on and I bring the R's up I get a tinny noise out of mufflers. just **** mufflers???? is there a fix besides replacing??Thanks for help.

[Bohemiangod]

you seem to have the same low end power lack that i have. I believe my car was has also had a JDM swap according to the previous owner. Regardless, I have no black smoke but I do hear a rattle. But yeah, anything past 3000 rpm and it jumps when stomped. Its a beautiful thing

[bp]

PLEASE HELP

[Milo (San Antonio)]

The "tiny tubes" that ran on the stock mid pipes were your AIV tubes. Did you plug them at all as well as the electronic component in each of the fender behind the splash shields.

Just wank the whole system, if you are unfamiliar with the kit and the layout then here is a link. http://www.twinturbo.net/ttnettech/aiv/aiv.html

But pretty simple, plug the holes, pull the system and plug vacuum lines.