i have a 94 cherokee xj sport 4.0L.

what it's doing now: after sitting for a while (like over night) when i turn the key it will start for only about a second and then die almost instantly and then it just cranks without starting no matter how many times i try.

what it was doing: as i was driving it sputtered like it was running out of gas but wouldn't completely die at first then it would die and i would be able to start it right back up and then it just died and i couldn't get it running for a week, i then unplugged the crankshaft position sensor (which was only 2 months old) plugged it back in then it worked for about 400 miles before sputtering and eventually dieing.
i took the CPS back and got a new one and it didn't change a thing.

the fuel pressures at 40. and im getting spark at the spark plugs.

things i've replaced in the last 3 months: flue pump (and filter), ignition coil, distributor cap, crank shaft position sensor (twice), and the computer.

any thoughts?