engine starts very rough when engine is cool ( after setting for several hours ) on 2004 Chevrolet Aveo

The other day I went to start the car and it would not even start at all. I have replaced the plugs and wires. I have taken off the breather hose and covered the throttle body with my hand to see what would happen and also sprayed some starting fluid in the throttle body,nothing has worked so far ! I'm thinking it might be some kind sensor ?

Asked by for the 2004 Chevrolet Aveo
is your service eng soon light on
sometimes it's on, sometimes it's off and every once in a while it will flash. took it in to the dealer awhile back and they said the code showed the thermostat so I replaced it. but the light still comes on some days and off others.
prior to it not starting at all in the mornings or after work it would start very rough, I could press the gas pedal a couple times after it started and it would smooth out and run fine. after the engine sat for servral hours it would do it again. ?????
i would ck codes again and see if they can get more data by testing it cold
I checked the codes and there was only 1 code....p1781 engine torque signal circuit. could this make the car not start ???
for some reason you are running extremely rich on cold start, poss coolant sensor
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