v12mac

I have been chasing a funky shift problem with my wife's IS 300 2001 Auto 115,000 miles we are the original owners since new.

It started about 8 months ago, I noticed the car would sort-of miss a gear or slip just a bit on what I thought was the 3-4 gear change.

Now when under moderate to WOT acceleration when it gets to this change it slips reves and wont grab the next gear unless you let off the gas.

Under light acceleration it seems to run just fine.

I did a full drain and fill of the trans with IV fluid had some discoloration but didn't smell bad.

I have been getting an O2 sensor check engine light but I cleared it and it hasn't gone off again.

Any thoughts? Some of the other posts I have read sugest that it might be TPS or Emissions.
Not sure if the trans software update was done or not.

Ideas?

v12mac

It might even be puling the throttle back a bit too.

v12mac

Buler? Buler?

v12mac

Just to close the loop on an old thread, this was due to a faulty MAF sensor. No codes thrown.