My car stops running after around 20 minutes
 

I have a 95 s500 sedan which stops running after about 20 minutes. The SRS/ASR/ABS lights are on at all times.

Any idea why this is happening? Some DIY tech friends suggested it may be the crank sensor or fuel filter. Any other ideas?

The alternator is brand new and the problem started a few days after the dealership installed the new alternator. Battery is a little low but car starts with a jump fine.

Thanks in advance.

Take it back to the dealer who did the alternator. They'll give you a dance, but should look it over, at least, and pull codes. OVP fuse OK? They go often in jump start scenarios. That would be easy ;)