my stock ka24de's being weird

[mkory]

Okay, I already posted this in ka24(d)e engine talk, but haven't gotten any replies, so I thought I'd post it here.

When I accelerate I hear a sound come from my engine. It sounds like a puff of air, almost like a blow off valve. It usually happens around 4,000 revs. If I'm driving it really hard, once again around 6,000 revs. It doesn't happen all the time, and I've tried to but haven't been able to find a pattern when it happens. I'm thinking maybe some kind of backpressure issue. Like I said, it only happnens some times. I can also feel it affect the power. When it happens, it's like I lose quite a bit of power(only for a split second, and just enough to feel) then the power resumes as normal. As far as I know the engine's never been modded, at least thats what the guy I bought it from said. A part of me thinks he might have done something, considering there's a mount for a laptop on the passenger side of the center console.

[StockerThanStock]

Check your vacuum tubes? I know someone who had a problem a lot like that and it turned out a vacuum tube somewhere kept collapsing, it'd make a loud sound like you described and lose a lot of power for a second or so. Look into that if you can.

[mkory]

Sounds easy enough. Where are these tubes that I need to be looking for, or where can I find somewhere that will tell me (for free)?