Intermittent starting issue on 2003, 4.2 S Type

I may drive about 10 miles, stop for about 1/2 hour to 1 hour. When restarting, it starts and dies. The RPM needle did not go up to the usual starting RPM. Rev it up mildly for a second or two and it is fine. It happened twice in about the last 15 starts. Once started it runs fine.
I changed the dirty air filter. MAF sensor? Fuel issue?