My Dad has a 2001 S10 with the 4.3 Vortec. It has a CEL with a P0300 code for a misfire. In hot weather it takes longer to crank before it fires up. Once it fires up, it idles rough. Once it gets running it seems to run fine in the higher RPMs and also feels responsive enough. On colder days it fires right up. I recognize that this could be a number of things, but I am wondering if anyone has experience with these and has seen any common issues with these symptoms. I don't claim to be a mechanic, but I like to do as much of my own work as possible. Thanks!