engine shuts down while driving on 1993 Toyota Previa

Hello, I've had my mechanic try to figure this out as well as 2 transmission shops. Here is what I know...transmission is in good shape and had a full tune up with no indicating problems. My problem... this happens while I am driving. The engine seems to shut down for a tenth of a second and it starts again than I feel a shift in the transmission. At the same time I notice the engine light flicks on then off. Engine has been checked as well as the transmission. Even had new oil and filter put in. Still does it. Any ideas what the problem could be? Afraid it will shut down going down a highway. Three places have check the engine light codes and finds no problem. Thanks.

Asked by for the 1993 Toyota Previa
So none of the shops have found any codes stored in the engine control module? Have any of the shops checked the technical service bulletins from Toyota?
I don't know. I will inquire and thank you.