C240 looses power and almost dies. Will die if you push on accelerator. Will idle rough if you don't. shut it off and let it set 15 minutes and it runs okay. this happens intermitently.

i think your fuel pressure regulator is not working or the injectors r jammed ( carbon deposits ) which causes low fuel amount that is y engine dies as soon as RPMs r increased because the injector r not spraying properly and if not that there is not enough fuel pressure in the fuel rail

Check your fuel pressure. If the fuel pressure is correct look at tps.

First you need to get the codes from the engine checked, this will point you in the right direction to what your problem is. You may find that your your car has misfired on a cylinder and the ecu in an attempt to save the engine will shut down the entire cylinder bank turning your v6 c240 into a 3 cylinder car. You have to shut the car down for the ecu to reset and it will start on all 6 cylinders again. This will continue to happen until you solve the misfiring problem. Causes for misfiring? Bad coil, spark plug wires or a bad Mass Air flow sensor. the coil and wires don't go bad often , but it the car has over 50K mikes on it, it is probably the Mass Air Flow Sensor if it has not been changed yet.( it will even affect the way the transmission shifts) believe it or not. I have explained this in the past in an answer to another related question on here. Look for it.

I highly agree with checking fuel pressure instead of spending $. Also the CPS should be next step cause your car shuts off with out reason.