I bought an '04 Silverado 2500 HD with 42k miles. Sometime when I start it ,it dies.If I wait a few seconds,it starts right up,but if I try to restart it immediately, it cranks for several seconds before it starts. It has never failed to start and it doesn't matter if its hot or cold.Its not consistent,it might start 10 times without doing it,and then do it every other time I start it.Do I have a problem with the fuel pump,computer or what? Thanks

 

check cable connections at battery, at starter, all grounds. clean/tighten as necessary.