Toyota Repair: 99 tacoma, voltage waveforms, o2 sensors

Question
QUESTION: Hi, I have a standard 1999 tacoma 4wd v6 3.4.  A few months ago, after I had an air filter replaced, the check engine light came on.  I took the truck to get the code read, it said the truck was running lean.  I got a tune up, changed the front o2 sensor, and also replaced the ignition wires.  got it reset, a few miles later the check engine light came back on.  I ignore the light, because the truck was running fine.  Two weeks ago, I noticed as I was getting on the on-ramp.  It was acting like it was choking as I press on the gas peddle.  The more I press down, the worse it got.  I pulled over and stopped, turned off the engine, a few seconds later turned it on again.  I was able to get on the freeway, but when I accelerate to about 26000 rpm it wants to bogged down.  It doesn't do this all the time, other times it drives great.  Please help.  Thanks

ANSWER: I need to know what the trouble code number is stored in the computer at this time.

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QUESTION: Hi, the code is po135

thanks

Answer
The Po135 code is for the #1 O2 sensor which was already replaced, there may be a problem with the cat converter which may be causing the power loss due to disintegration of the material inside of it, the converter operation can be checked by using a scantool that can show the voltage waveforms of the front and rear O2 sensors or the converter can be removed and inspected for any loose material inside. This code can also be triggered by another engine malfunction but there should be other codes besides the PO135.