Symptom....The car runs like a champ, it idles fine and starts great, Above 3000rpm or under moderate load (lead foot). Above 3000rpm I can hear the motor ping and I feel that the car is taking a lot of timing out and the power disappears. It sounds as if it is running lean. I had a similar problem three months ago...I traced it to faulty fuel injectors, so I replaced them with accel injectors. This solved the problem for three months. Then one day I stepped into the throttle hard and my tire squealing high rpm horsepower was gone...my low end was not affected.

Things I've checked
Injector Impedance
Fuel pressure
MAF

 

is your timing advancing under load something to check

 

start with the cheap stuff, change the fuel filter, check your fuel pressure, and check your base timing. you might also have a major vaccum leak, this would cause your engine to run really lean under load or at higher RPM's do to the fact that air is entering the engine and the computer doesnt "know" about it

 

Also check for a restricted exhaust (Bad cat or damaged pipes). My cat was clogged and the car acted fine at low RPM but as soon as the RPM increased at WOT the car started to loss power. No air flow no power.