One problem related to speed control linkage has been reported for the 2004 Toyota Sienna. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2004 Toyota Sienna based on all problems reported for the 2004 Sienna.
When attempting to accelerate after braking/slowing down there is a period of several seconds with no response from the throttle and then suddenly the vehicle jerks hard and accelerates. When merging into traffic this can pose a serious safety issue. The Toyota dealer advises this is a normal condition as the vehicle "drives by wire" and has no mechanical throttle linkage. This vehicle didn't have this issue when we purchased it. This problem developed after we had driven it for a while and has progressivly gotten worse. Other manufacturers also use the drive by wire components and do not have this problem I find it hard to believe that Toyota considers this a normal condition.