2000 Chrysler Concorde 6 cyl Two Wheel Drive Automatic 101031 miles

I had previous wriiten about my concorde. I took it to a transmission place. They hooked it up to the computer and said that there weren't any codes, and that the sensors were working.They did say that they could not read the engine. I'm still having the same problems with it. It continues to stall without notice and when I'm driving it , the tachometer will go to zero, and the engine stalls for a few seconds, then it will thump or thud and pick up speed again.

Is the check engine light on the dash illuminated? If it is, there is/are code(s).

For Chrysler vehicle, the scanner has an option to check powertrain or drivetrain. As, they were a transmission shop, they probably scanned your drivetrain (transmission), instead of the powertrain (engine) computer. If they did say that they could not communicate with the engine computer, that is something that you have, probably a Chrysler dealer, to have a look at.