annoying noise hard to detect

i have this annoying whirring/whooshing noise coming from the engine bay when i accelerate around 2000rpm and disappears at any rpm above or below this. when im on the highway and the rpm stays steady at 2000rpm, u hear this noise... it sounds like the fan clutch for those of you familiar with the loud fan noise that sounds like a truck...but not as heavy and only at 2000rpm....fan clutch is ok since it was replaced with ac & main tensioner, idler pulley, belt, alternator, wp, and thermostat. i know its not the fan cause if i remove the mechanical fan start the car up and rev it to 2000rpm, i can still hear the noise...any suggestions or links would be greaty appreciated....also if it helps, this car has a weird idle problem during cold start in the morning...not cold weather. once sap turns off, car sometimes will have idle surges every 5-10 seconds. it will eventually either warm up and idle will stay smooth all day wihtout any misfires, or sometimes the idle jolts will cause it to stall. once restarted, the car is absolutely fine. car seems like it has weak low rpm (below 2000-2500rpm) acceleration.
other things changed:
ccv with all hoses
lower boot
cleaned icv & disa