Hello. The low power situation can be caused by a few things. Milage is not always the issue, age is a another factor. And I would not have replaced those sensors, they don't age and are good for 60k!
First of all, you are using premium fuel, right? If not, there ya go. Use some injector cleaner and a couple tanks later you should be restored.
But lets assume you are using premium, here are some maintenance issues:
•:qFuel filter, probably not it, but they can die of old age, are cheap and sorta easy to replace.
•:qAir filter, again, cheap and easy to replace. I do mine every spring.
•:qSpark plugs are fine, your factory ones are good for 100k but I would replace them at 75k or so, assuming you have the car that long.
•:qMake sure your trans fluid is at the correct level and does not smell burnt. With the car up to operating temp go through the gears, reverse, forward, etc a couple times and while its running, check the level. Make sure you are on level ground.
Some mechanical items could be:
• IMRCs are stuck on the open position. When open under 3k RPM the engine is literally robbed of power. They can get stuck open if the car is not ran a lot or puched over 3k a lot. They gum up, stick and casue all sorts of performace issues. Over 3k they are suppose to open so once you pass 3k RPM the car suddenyl springs to life. They can also stick closed. There is a good chance that this is you issue.
• Vacuum leak. Try CAREFULLY spraying a little ether, starting fluid around the engine bay and see if it suddenly revs up or if the idle changes. THere is a good chance that this may also be the problem. The vacuum is strongest when idle, but if you hav a leak you idles is usually un-even.
• Damaged COP boot. Unlikely, but its a milage and age issue. If a coil boot cracks the spark is arrested and you wont get the power you need. Typically though you will feel a rough idle, but this is not always the case.
•:qDamaged COP. Very unlikely but possible. If one spark plug is not firing right it will throw things off a bit. This is more common in coil packs though, not COP.
• Fuel pump is failing. These buggers act weird. I have seen where they idle bad yet rev high without a problem and it turns out ht be to the pump, go figure!
Anyone else got some ideas?