3RD vote for a fuel pump push rod being worn. I had this problem before on one of my other Hemi's when it sat for a period of time. Seems it would not give it large enough pump shot while cranking. Once fired it would idle & run fine. Once it changed out for a new push rod the problem went away & start right up every time afterwards. Even seemed to pull harder at higher RPM also, so it must have been losing fuel pressure at high RPM's also.