"96 Dodge 1500 Ram truck intermittant spark

I am getting an intermittent spark with my Ram 1500, 5.2/318 4WD auto.
When I crank the engine, I get power to the coil feed wire for about 3-4 seconds but after that, no power. I replaced the relay in the power box, all of them actually. The relay is kicking out after 3-4 seconds and I lose the power to the coil.
If the truck doesn't start on the first crank, it won't start at all. I can crank it forever and no spark. When the truck does start, (on the first click), it runs fine.
This condition seems worse when the engine is warm.(coincidence??).
It gave me a couple minor problems over 2 weeks ago, (extra cranking to start when warm), but nothing serious. Then last week, after shutting it down for about 20 minutes, no start. The engine then flooded so I waited till later that day to try again and it took off on the first click and ran fine till I shut it off.
Then the same condition all over again.
I replaced the coil and crank sensor.
Have had it to the local repair shop but they couldn't find the problem or a plug for the diagonstic device nor any evidence that it ever had one.
No codes in the dash evident.
I had it towed home and am trying to fix the problem.
I know the PCM is ok because when the engine does start, it runs well, no misfire or lack of power.
Fuel pump is working.
It's this intermittent problem that has me stumped.
Any body have this situation before?