[Mr. Ugly]

Originally Posted by KlrStng

[...] it could be a vacuum leak or a leak in the intake air tube after your MAF housing. When you push the gas a little, if it is leaning out, you could experience a loss of power, or worse, there might be a slight detonation from the lean condition causing the computer to pull timing, resulting in the engine "bogging" and losing power. If the leak is small, once you get into the throttle more the amount of air coming from it would be small enough to become negligible and not affect anything, restoring power. I would start there..

Yep, check for vacuum leaks.

[Ragnar]

Don't overlook the seal around the MAF unit itself. One of my screws holding the MAF to the CAI air tube came loose. There was a huge gap and the car was running really bad. So check that as well.