2005 grand prix series 3. It starts first thing in the morning and when temp. Guage is at the half way point. No check engine lite on.I have checked spark and fuel pressure. All ok. When I unplug the etc it starts every time. I checked the etc versus resistance when it doesn't start. This is what I got 57 degrees celcius at 597 ohms. When it does start it will run fine all day till I shut it off. The only other thing I notice when it is hard to start is a slight hesitation pulling away from a stop. Any ideas guys this is tormenting me bad. There are no coolant leaks.
