2004 model with auto transmission. Believe first owner was Florida government. Purchased 10 months ago with 110,000 miles and can't find any evidence to believe that odometer is not correct. Underneath of vehicle appears that it sat up outside for an extended period of time as there was a light coat of rust everywhere underneath. I gave this info as an estimate of 110,000 miles also on transmission. There is a new transmission pan seal. Fluid level is good ( at idle and hot). After 7,000 miles of driving after purchase, the fluid is bright red without any burn odor. .Problem: Occasionally, while in overdrive a quick, slight jerk is felt between 50-60 mph. I have not been able to duplicate this by backing down the RPM with accelerator. This is not a very noticeable jerk, but I can feel it. In the last 3 months, the frequency of the quick, slight jerk has increased. There has never been a check engine light indicating a transmission code is present. To rule out an engine misfire, I drove it without the OD engaged and did not have the jerk in the vehicle. What might be causing this and possible required repairs?

 

Do the engine RPM's change when this happens, like shifting into or out of overdrive?

 

It happens so quickly, I don't notice any change in the sound of the engine and too quickly for me to see any change in the tachometer.