Sputter at 4500 - 5000rpm in 4th & 5th Gear
 

My car sputters a bit under hard acceleration in the 4500 - 5000 rpm range in 4th and 5th gears. After it passes 5000 rpm's, (maybe 5200 or so) it pulls hard and smoothly.

Any idea what could be causing this?

Random ideas/thoughts: Low gas, cracked fuel hose, vaccum leak

Are you sure it is that high of a RPM, I believe thats after the extra ports open .So probably not that .

Yeah, I was on the highway for 3 hours last night, tried it out a few times. It is definitely that high of RPMs.

Also, the car had 3/4s of a tank of gas (premium, obviously) while I was testing this out. I will get the fuel hoses looked at, as well as vacuum lines later today. Any other ideas?

fuel cut?

I've got a Fuel Cut Controller.

i have the same problems man exact same rpm range too i thought it was crappy gas, electrical maybe. i have full 3" ehaust with the FDC plugged in is aftermarket exhaust to big for the turbo to push if that makes any sense please help me ,, have you found any answers?