Cranks will not start

I have the truck listed above 1500 with a hemi. It shut off at a red light one day and I assumed it was out of fuel since the gas station is where I was headed. Well, I got it to start back up but had to keep the accelerator pressed. Drove right across the street to the gas station; it spitted and sputtered all the way. I put fuel in and would not start. Pushed it out of the way. Upon inspection found that there was no coolant in the reservoir or radiator. I out 1 gallon of 50/50 and 3 gallons of water in it. Let it sit for bit. Still wouldn't start unless holding accelerator to the floor. Had it towed to my house. Pulled and checked all injectors, replaced spark plugs and wires and still have the same issue. Everything I have read so far suggests busted head gasket but oil looks fine and no signs of any leaks underneath the vehicle and no smoke ever came out of the tailpipe. So I want to look at other possibilities before pulling the heads and changing the gaskets.