Hello,
I have an intermittent failure of throttle after driving 100 miles or so when outside temperature is extremely hot (typical Texas hot summer day). All of a sudden, the car acts like I let my foot of the gas pedal but it is not the case and car finally stops (note: engine is still running). It is like some sensor (throttle position sensor?) not sending right information to the ECU or what ever module that needs that information. After reading lot of posts here and lot of goggling around, it sounds like there could be any number of problems, like air mass, throttle position sensor, o2 sensor, fuel filter? etc. I took it to a Mercedes dealer and he kept the car for two days, checked all of these sensors and told me they can't do anything since the car is not throwing any codes (apparently the OBD II reader did not read any code) and they gave the car back saying there is nothing they can do with out code . Now that the weather is not that hot, the car is driving fine (drove about 350 miles with no problem) but I hate to continue driving the car knowing well there is a serious issue with it. I bought a cheap OBD II reader and have it in my car in case of this issue comes up so I can try to read the code.

I don't know much about cars... can any expert in this forum give me advice on how to go about troubleshooting this problem to find the root cause?. Any help would be greatly appreciated.

Thanks