Q&A

 Master

It could be many things hard to guess without being able to able to experience the problem first hand or do some basic diagnostic tests. It could be fuel starvation, it could be ignition system failure (bad coil or spark plugs). I work on a lot of Toyotas perhaps the air flow sensor is failing in its performance, I have seen these fail and not set a code. A scan tool is required to measure key engine sensor values and see if they are all in range.

 Enthusiast

Several reasons why a car jerks when accelerating read it here http://www.cartechhome.com/2010/07/car-jerks-when-you-acc...

I ran into the same problem and researched it. I cleaned the MAF (Mass Air Flow) Sensor with some rubbing acohol and a Qtip. I have a 2000 Toyota Echo.
Please read the links below:
http://wiki.answers.com/Q/Where_is_the_mass_air_flow_MAF_...
http://www.toyotanation.com/forum/showthread.php?t=252676

It worked for me...for now...I drove the car immediately up a very steep hill with no acceleration problems.

Tips:
Use a few Qtips and try not to double-dip
Clean until no dirt comes up on the Qtip and do not use a dirty Qtip, hence the multiple ones needed
You use a hair dryer (cool and/or warm setting) to help dry things out (if you do not want to use compressed air or do not have access to compressed air)
You may be able to use the cold spray they use for cleaning electronics/keyboards/computer equipment that they sell in Business Supply stores...didn't try it because I ran out)