Recently my 4Runner (290K mi) has developed a strange issue. This starts at highway speeds, once the engine has warmed up. It’s a re-occurring single jerk, intermittent and irregular, feels similar to another car that had trouble choosing its gear, where the transmission dis-engages and then rapidly re-engages. No loss of power. The first time this happened we turned cruise control off, and it didn’t happen again for the remaining 400mi of that trip. Then yesterday we had gone about 20mi when it started again. Turned OD off (no cruise this time), which seemed to help at first, but then we turned off the highway and drove at around 30mph and it just got worse. Rapid-fire bursts of stuttering. No change in engine sound and it seemed to rev fine when I pressed the gas. We barely made the last mile to our destination. After sitting for 3 hours, the drive back was uneventful, including highway speeds. Only difference was the ambient temperature, which had dropped from the high '80s into the '70s. There are no warning lights on. The car was JUST serviced before the 400mi trip. Any ideas?
Sounds similar to the symptom for torque converter shudder. Ask you shop if there’s a way to temporarily turn off the TC lock-up function. If that solves the problem, you know what’s causing it anyway.
Common sense says to check the transmission fluid level first of course.