One problem related to engine has been reported for the 2003 Toyota Avalon. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2003 Toyota Avalon based on all problems reported for the 2003 Avalon.
Our 2003 Toyota Avalon has experienced several occurrences of sudden acceleration. My wife took the car to our Toyota dealer and both times they said that it was due to the floormat sticking under the gas pedal. The mat was removed and it still has the problem. While I was driving it down the highway, I let off the gas to slow down and it started to speed up. I put the car into neutral and the engine started to rev up and down from 1000 rpm to 2500 rpm. This continued for a couple of minutes until I was forced to pull over to the side of the road and turn the engine off and restart it. (this is always the fix. . . Turn off the engine and restart it. It seems to reset the computer). This problem started over a year ago and continues to occur almost monthly. This vehicle is not included in the recall and even if it was, I don't feel that the problem has a fix, yet. We have to continue to drive the car because we can't afford another one and the resale value has plummeted. Just last week my wife was stopped by a dps officer for speeding from a stop light. She did not even have her foot on the gas pedal. She explained what had happened and was not ticketed.