Transmission slips then reenages at high speed

I have had at least three mechanics look at this problem. I had my transisson oil changed and checked. No metal is in the pan and I was told the transmission is in great shape. My problem…while driving on the highway it seems that the transmission will slip out of gear and reengage with a small jolt. Sometimes the car engine will shut down at a stop light. I maintain my van on a regular basis. The computer shows nothing wrong. I am wondering if the computer is not working. I had the air bag light on for a long time and now it is off. I have called and explain to Toyota about this problem and they say the only way to figure this problem out is to drive it. They drove it and nothing happened. Has anyone experience this problem? It is a 1993 Toyota Previa with 183,000 miles on it. Thanks.

The transmission may be fine, but the torque converter could be faulty. Either something is telling the converter to engage (or disengage) at the wrong time or the converter itself could have an internal problem.

Was one of those mechanics a transmission specialist?

Yes, he is.

“Sometimes the car engine will shut down at a stop light”

I think that you should focus more on that for a while rather than thinking about the transmission. If you have an intermittent problem that will stall the car then that condition might “feel” like a disengaging transmission when you’re cruising along. It would be called a “driveability” issue rather than a transmission issue.

A torque converter lock-up, unlock problem could be the entire issue… Is the vehicle worth the $3500 it will take to fix it??