340 fuel issue stalling or excessive crank

Morning all.
I have a 70 340-4spd dart w/3.55:1's.
I am running a holley 4160 (4777-7) 650 cfm on my 340 x-head with mopar aluminum intake. Headers and flowmasters. Purple cam, motor has been worked.
Occassionally i'll take an extended run down the highway and get off the exit ramp, come to the light and it will seem to run out of fuel or want to stall. I will have to extended crank with foot to floor to get to run. Then drive fuel miles before it works out. The other scenario is on easter weekend i took it to my mom's and it was in the mid 80's that day.
I parked there for 30-45 minutes. Went out to start and it cranked for ever before it fired had the pedal to the metal.
Is it running itself dry? Do i need to run a fuel regulator and guage?
I have mopar electronic dist., coil ,with orange box which is showing good spark. Should i upgrade electric system also? thx all Joe in CT.