engine shuts off without warning when driving and/or stopped

In December 2017 my van started shutting off without warning when driving or stopped at a light. The lights on the dashboard will sometimes flash before it shuts off but not all the time. When I do get the van to re-start the rear A/C blows high even if it was on low. I am a realtor and drive people to see homes daily. I took my van to the dodge dealership and they told me it is not stalling on them so they cannot diagnose the problem. I have researched this and see that the TIPM is normally the problem. They told me I will have to bring it back when it is stalling and there is nothing they can do.