2009 Town and Country really rough idle and engine shut off

So this is going to be quite long. About 2
years ago our town and country started to
have problems in cold weather, we live in
Michigan and right around November the
engine started to rough idle and then pop
while sitting. We had a close friend who is a
mechanic look at it. He had the van for
months and never had it fully fixed. We took
it back for the summer and it drove fine. And
again right around October/November rough
idle, and then the coolant would empty after
a few days. So we had a real mechanic look
at it, he replaced the entire engine and
cleaned everything. We took it back after
about 3 months. Within a week of taking it
back same problem occurred. Stopped for
the summer months and now that it’s cold
again the engine is having rough idle issues
again and this morning the engine shut off
while I was idle at a stop light twice, the van
itself stayed on so I know it’s not a battery
issue the engine itself shut off and the rpms
went to 0. Anyone have an idea what could
be wrong? We know the coolant leak is from
a hose that goes into the engine which is
getting fixed this week, but to be honest I
don’t think that will fix the issue.