94 pickup won't start warm (sometimes)

I have a 94 extended cab 4x4 22re. It starts fine when I first start it, but after I drive it 5-10 miles and turn it off sometimes it will not start it drags like the battery is dead. after it sets for about 30 minutes or so it will start just fine. I have replaced battery, battery cables, starter, fuel filter, spark plugs, and changed the oil. it has not helped at all. Nobody seem to know whats causing the problem. Any help would be greatly appreciated. Cold Start valve?
Thanks

did You solve this question? I am wondering if you have the security key. I cant think of what it is called right now, mine is under the steering column and you pull it out and it wont start. I have had it work lose a few times. I dont know if they all have this or it was after market. Right now mine is dead, nothing and just suddenly, it is like that key was removed but it is not.