look to see if your intake manifold is gummed up with residue
There are multiple things that could cause this, your best bet it to take it to a mechanic and let them check it out.
Could be a fuel pump going bad or a clogged fuel filter,
A faulty muffler will not cause this but a clogged catalytic converter will.
Look for a hole in the PCV valve hose on the backside of the engine.
Could be many reasons. If the check engine light is illuminated, check for codes first.
A bad fuel pump will cause your vehicle to not start or sputter and then stall. A dirty air filter can have the same symptoms.
If car stalls out when accelerating above 40 MPH, it can possibly be caused by fluid leaks. Another reason can be a defect at the transmission.
They start to sputter,stall and stop running.
TCC Solenoid.
Check the fuel filter or the fuel pump.
Lack of fuel it needs to operate
Lots of things. From misfiring spark plugs to incorrect timing to deposit build up.