loss of power and whooshing air sound at high RPMs

Hi everyone,

I've lurked around quite a bit for a few years, but here's my first post:

Truck: 2007 single cab pre runner. 4-cylinder manual.
Aftermarket: Has a K/N filter and a flowmaster exhaust

It runs fine until I put some stress on it. It doesn't matter what gear. As soon as I get down on the accelerator, it starts releasing air from somewhere and just bogs down. The air sound is cyclical, like, sh,sh,sh,sh,sh,sh,sh,sh,sh... really fast. The sound also changes. Sometimes theres a continuous sound in addition to the cyclical sound. I'm pretty sure the sound is coming from near the engine, not underneath the cab, but not 100% sure. Anyway, I think that's all I can tell you about it. Actually, one more thing... The tank of gas before this started happening, I added a can of that lucas oil fuel additive.

I checked the air filter, hoping that maybe something was just stuck in there. No such luck. I was going to change the fuel filter to see if that helps. I wanted to check here just to educate myself before I visit the mechanic. Any advice would be much appreciated. Thanks guys!

 

weak engine and windy driving conditions?

 

I can definitely see how someone would find that funny.