I know this is a common issue people have. I've done quite a bit of research but I can't seem to figure it out. I've got a 1998 Chevy K1500 with a 5.7 Vortec tuned by Blackbear Performance. I've had a misfire issue for quite a while now. I finally thought a had it figured out last weekend when I replaced the crankshaft position censor. It went away for a while but it came back today. It doesn't misfire until it gets up to temperature but it also doesn't do it all the time. I replaced the engine in late September of last year and have only put about 12,000 miles on it so far. Since the swap, I've replaced the maf sensor, crankshaft/camshaft position sensor, knock sensor, distributor cap/rotor, spark plug wires, and spark plugs. All of those parts were either AC Delco or Delphi. The fuel pump also got replaced last July with a Delphi unit. I upgraded the spider injectors about two years ago but they were BWD. I'm kinda stuck and not sure where to go at this point. I did just order a bluetooth OBD 2 scanner and purchased TorquePro to help me out and see if I can make any progress. Anyone have an idea as to what it could be or point me in the direction of what I should be looking for diagnostic wise? Thanks in advance.