Engine knock/rattle vs. fuel injectors??? Any help?, Video and description... Options

[celicakitten]

So I've had my car for three months now and still cannot figure out what this noise is! I'm by no means a mechanic but have common sense around cars, celicas inparticular. It's a mostly stock 7a-fe with 194k and 5 spd tranny. The car runs fine, and since I've had her changed the oil, spark plugs/wires, exhaust manifold/down pipe(original was cracked), and have had no other problems...not even a check engine light. I can't find anything loose that would rattle, but there is a significant power steering fluid leak.

http://youtu.be/FOrH0HC7l5w

Please see the video I put on youtube to hear the noise, which is most notable on a cold start and anytime I'm constantly holding revs over 2500rpms, but will stop if I floor the gas or let off it completely...It's very annoying on the freeway(but isn't noticable with the radio on! ha!). I'm thinking maybe a bad piston ring, or possibly something in the fuel injectors??? I should also say the noise does seem to emit from the passanger side of the engine bay. I'm worried it may be time for a rebuild as I do not know how the previous owners treated her. If that is the case my biggest challenge would be finding someone I trust to do the work, but I'm sure you guys can help point me in the right direction for that!

[Special_Edy]

Without seeing it in first person I would want to guess that something is loose, an engine mount for example, that is rattling when the engine reaches a certain harmonic or RPM. I once had a very bad knock on my pickup truck and after maybe 15-20 "expert" opinions it was determined to be the crankshaft. I pulled all the main bearing caps and plastigauged them just to find out it was the three bolts that hold the torque converter to the flexplate that were loose. Moral of the story is that its usually the simplist fix, not the hardest one.

If you want to doublecheck the injectors-
With the engine idling pull one spark plug wire at a time and listen for a drop in rpm. The cylinder that causes the rpms to drop the least has the potentially bad injector. Make sure to use a rag to pull the wires so you dont get shocked.
Now that youve located a possible bad injector you can remove the two bolts attaching the injector rail to the cylinder head. Remove the bad injector and swap it with one of the good injectors. Reattach the fuel rail and retest for dead cylinders. The dead/weak cylinder will have moved to the same location as the bad injector if the injector is indeed bad.

Hope this helps...