I have a 98 silverado that starts perfect when cold. But when I drive it for a few miles and it warm up, when I go to restart the truck sometimes there is an issue, particularly before the thermostat opens and the engine is around 130F. The starter turns fast and the battery is new, but after the starter cranks the engine about 3 turns then the engine putts at me and the starter stops turning. I don't believe its the starter because it cranks fast, and the battery is new putting out around 12.7V. After the truck is fully warmed up and coolant is circulating through the entire system it also starts fine. So during the warm up process if I turn it off its hard to start. This leads me to believe it may be the coolant temperature sensor. The service engine soon light is on and im going to take it to my mechanic this week, but a sensor is only $30 and If that sounds like the problem to you guys I may go buy one and change it myself and see if that helps. PS wheres it located, Im currently searching for my repair manual and cant seem to locate it. 350 vortec. Thanks.