96 Benz ran out of gas other day, got it filled up & drove home (20 miles). Next day drove about 40 miles, left car running in park for about 15 min, when I left car was stalling like it was running o

Possible emissions problem. get the ecm scanned & go from there.

I think you got hold of a batch of stale gasoline, have seen it many times. This happens this time of year because they are using up all the winter blend gas so they can switch to the summer blend..

Running so few miles has accelerated the aging of the battery - the battery never had a chance to fully recharge in such small trips -  so now you have to replace it a year sooner than usual.
Just replace it.

could be your fuel filter gummed up from the old gas

as silly as this sounds, check your gas cap and make sure its tight. its a good idea to get someone to scan it to verify fault(check engine light). it will give you piece of mind as well. happy holidays

Car not starting or turning over indicates towards multiple possibilities. It can be issue with battery or weak battery. But if battery checks out ok, then it can be starter issue or faulty alternator or problem with low fuel pressure or no spark at spark plugs due to dirty spark plugs or faulty ignition coil or injectors getting cracked or dirty and needs to be cleaned.

To confirm the problem, the basic troubleshooting is required.

Click this link below and follow the troubleshooting:------

http://technoanswers.blogspot.in/2012/02/car-starting-issues.html

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This will help.

Thanks.

Run a bottle of strong fuel system cleaner through a tank, it's common to get bad gas.

Check the harmonic balancer

change fule filter if nothing changes do fule pressure test

If fuel filter hasn't been done lately I would start there & if you can, have fuel pressure tested while your at it. You may have tired fuel pump but pressure test will confirm. If you recently filled up somewhere different last time you got gas, I'd also try some "Heet" or similar just incase you got a tank full with some water in it.