I have brought this problem to the forum before and just cant figure it out.
My 1996 discovery has this problem where it sometimes upon startup will die right away or idle rough for a while. Seems to get better as it is drivin but one time at highway speed it would every 25 sec or so give a "hicup" of hesitation. Now this problem happened off and on for about two months and then stopped for about a month. and now out of nowhere its back. I have cleaned the stepper motor, checked the air filter, cleaned the throttle body and changed the fuel filter. I also checked and cleaned the hoses on the valve covers. Also no dash lights are comming up and other than this problem it runs very smooth. I use 92 octain gas. Any help would be greatly appreciated!
Thanks

 

Two things that come to mind would be the fuel pump relay, which are know to act up prior to failing.
The fuel pump it self, in one of two areas, bleed down of fuel pressure because of a bad pressure relief valve and the general lack of adequate fuel pressure.
You might want to start look at the pressure with a fuel pressure guage.
Mike