This is a common problem on many GM vehicles from this era. The engine either all at once, or progressively gets harder and harder to start. On my vehicles once it was started it ran as smooth as when it was new but on many you will see rough idle as well. The most common cause for this is typically a failing FUEL PRESSURE REGULATOR. It is fairly easy to diagnose on most vehicles. But on an 03 Chevy you need to remove the upper intake to get to a normally external part. Once your in its pretty easy to see if it has a problem or not. You should not have fuel in the upper intake. If you see gas everywhere you know you were looking in the right place. If you don't it still doesn't hurt to replace the fuel pressure regulator since they are only made to go about a hundred thousand miles. Thanks GM. Mine was a text book example and failed at 105,000. Its typically one of the first places a good home mechanic will look since it is cheap and has a high failure rate. Should cost less than $50 although when you see it it looks like it should cost 50 cents.

Yet another problem with my 2003 Chevrolet Silverado. My truck would turn over but would not start up. I had to hit the gas pedal while turning the key to get it to start. Brought it to the local Government Motors dealership in hopes that they could work their magic for the fifth time since purchasing this vehicle from them in 2005. Ahhh yes! The grease monkeys hooked it up to their top secret diagnostic computer and found out that the fuel pressure regulator was not working. The Government Motors service guy attempted to smooth things over with me by acting concerned and saying "It is the best case scenerio, its just the fuel pressure regulator and not the fuel pump." I felt so much better! After all, it was only going to cost me a mere $284.00 for 45 minutes of work. Thanks Government Motors!