I have a 94 K1500 with the 5.7 that starts fine but stalls after about a minute. It will not start again right away. before it dies I noticed that the tach starts jumping up and down. once I get it going and warmed up it seems to run just fine. I found that i do have spark and the fuel pump is working. i also changed the temp sensor by the intake. Any suggestions on where to go from here?