Truck will not start easy when motor is warm

Hi, I have a 95 GMC Sierra 1/2 ton with the 5.7 in it. In the morning it starts fine but if I shut it off for a short period of time before it has a chance to cool down I have a hard time getting it to run right. Seems like it only wants to run on a few cylinders and it will smoke and I smell gas. I have to keep reving the engine until it smoothes out. For some reason it doesnt seem to do it as often if once I get in it I turn the key to the "on" position for around 5 seconds then start it. The truck has 157,000 miles on it. Thanks for any help you can offer.