98 Disco runs then wont start

[discofun]

Forgive my Newbness. Here's the issue... Have never had a problem with my 98 Disco Annivesary before, other than replacing the water pump, fan, hoses, etc... Was running great. After driving for 40 minutes it lost power and died. After about 20 min it started back up and I got another 2 miles before it died again. No warning lights, no odd noises or misfires.
Now, it will start and run fine for 10-20 minutes then die. Wont start back up for a couple hours, then repeat the process. I was told to check the pressure on the rail and its fine. Did some research and found out about faulty "safety switch" and checked it too. Seems fine as well. Now, I'm at a loss. Can someone please advise me what to check next? This is our family vehicle and the kids are driving me nuts about being at home for the last week.
Truck has 4.0 v8i engine. Has 84376 miles. Has been serviced regularly. PLEASE HELP ASAP...

 

[Chanwanga]

I actually just bought a 97 Disco and had similar problems. when you say "safety switch"...do you mean the fuel cutoff inertia switch?? Because I had to replace not only my switch, but the wiring harness as well. Hope this helps.

 

[Disco Mike]

Bad crank sensor or possibly a bad fuel pump relay, either of them could cause this. Make sure to change your fuel filter also.