I was driving home this past Tuesday and had about 1/8 of fuel left. I was in 4th gear when I was going uphill so I stepped on the gas to make it downshift to 3rd but it had problems downshifting. The car was shaking/stalling and I thought it might've been because of th low fuel level. So the next day I fill up the tank and drive the car home in the same street so I tried it once more and it did it again. I normally drive the car in OD, I don't manual shift it at all. The car doesn't have problems shifting from 1-4th gear, it's just the down shifting problem that I have when stepping on the gas to make it automatically downshift. This generally happens in 4th-3, I haven't tried in on the other gears.
What are things I should take a look at?
Your help will be much appreciated.

 

Sounds more engine performance related than transmission issues.

 

Agreed. A bad engine sensor will cause the trans to shift erratically, particularly the TPS or MAF.

 

Alright so I went ahead and drove the car right now. I stepped on the gas pedal all the way and the car seems to "choke". I did a small pull and around 4k rpm, I didn't see exactly how many rpm it choked again. Can this also be the fuel filter? Or like you guys said a sensor.

 

The fuel filter is a place to start, How many miles does the filter have on it?

Next is to check fuel pressure, Scan & check TPS voltage, Unplug the MAF (Unpin the yellow wire on a 5 pin MAF) & test drive.

 

I honestly don't know, I bought the car about 1 month ago. The fuel filter is the first thing I'm going to change tomorrow.
How exactly can I scan & check th TPS voltage?
So do I test drive it with the yellow wire unpinned?