1995 sc400 152k when traveling 65-80 on highway going down a slight downhill, low grade, with the cruise on or cruise off the car (engine) will do a quick jerk two times. On a 90 minute trip this may happen twice. It is like a grabbing affect. Does not happen uphill or level cruising. I had a complete tranny flush two weeks ago and this grabbing scared the heck out of me, thinking the tranny was giving up but after happening again it seems like the engine.
Any clues??

 

you may be feeling the lock up in the converter--locking and unlocking.. seeing as your going on a slight down hill, i think the trans is getting confused..?
there is no direct drive in auto trans--unless the converter locks.. this is done for better gas milage..this is normal operation.. but im just guesing here..
im sure youl get some more things to look at..

 

Hey, thanks for the possible diagnosis. I have not asked my local mechanic to take a test drive yet. I should probably loan it to him for weekend. Any other tranny mechanics out there for theories?