Nissan Repair: Bogging Engine & shakey Tranny -01 Sentra SE, vacuum test, o2 sensors

Question
Hello Von,

I sent this e-mail to Calvin, but also wanted to send it to you as you have specialties with engine & transmissions.
I am hoping that you, along with Calvin may be able to assist me!!!!

Thank you,
Irene
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I have been taking my car to a few mechanics regarding my issues.  My engine is bogging...feels like there is no power coming from it somedays.  It comes and goes....right now it's running better, but not perfect.  On the bad days, I can not accelerate to speed limits, and on an uphill I loose speed.  I also have to lightly tap the gas peddle to accelerate..if I floor it, it decelerates.  Its very frustrating to me and my mechanic.  I had many sensors tested instead of replacing them as I'm out of work right now & cant afford to replace all of the sensors.  My mechanic has done what he cld think of...he is frustrated with my car & not being able to diagnose it.  I had a second opinion done as well...same thing happened, no resolution. My engine codes currently read: a mis-fire, and running too lean, TPS (which was already tested & fine)

I have had the TPS and MAF chkd. My plugs were looked at. Both O2 sensors are new (due to PCM codes) Fuel pressure test was done...vacuum test was done.  The timing was also chkd.
I cant even remember the rest that was done.  I had a 2nd shop chk those same parts....still no clue.  I even took the car to an auto electrical specialist...and that mechanic told me it was mechanical, not electrical.

Can my PCM be fried?
Will it cause this?
How can I have the PCM tested?

I also have a 2nd gear ratio code up for my tranny. I don't know if this is a separate issue or due to the engine issues.  My car jumps into 2nd gear pretty hard. all the others seem fine..except for a bit of hesitation getting into gear(due to the engine i think)...but the new thing now is that when on the highway and I take my foot off the peddle...i can feel the tranny slightly jumping and jolting as it gears down....it shudders and I feel a slight deceleration.  Can this be a minor issue?  My Transmission is approx 5 yrs old...was already replaced once under warranty.

I am so frustrated. I cant afford to put a lot more into this car.  I am looking for a new vehicle, but I cant sell this one in this state!!!

HELP  :(
Any suggestions on what I should have looked at next?
Camshaft position sensor? Do you know what the proper voltage and resistance readings shld be for my Nissan's year/make/model?


I feel that this major issue is probably something so minor....but what?

Thanking you in advance,
Irene


Answer
Irene,

I would first check the basics like fuel pressure and the ignition.  The other thing I woul do is re-run the codes to make sure the knock sensor and mass airflow sensor are good.  Have these checked and email me back.  I would not say the converter since the problem comes and goes.  I do not think the transmission is messing up.  I would think the poor performance of the engine is causing the shift issues.  Also, I would make sure the intake hose is not cracked or loose.  That is the hose between the air meter and the throttle body.