Fuel problems

Ok folks, I changed my sedimentor and fuel filter, I filled the filter up but didn't have enough spare diesel to fill the sedimentor.

Now, the engine (disco 200tdi in a LR 90) runs! But, when I accelerate the engine revs and then splutters and occasionally cuts out a few seconds. Now by my thinking, the engine isn't getting enough fuel to it... So, is it:
1. air in the system from the sedimentor not being bled
2. The Lift pump giving up the ghosts and not supplying though fuel
3. Something I hadn't thought of!!

How do I check all of these things??

The sedimentor is utter crap they cause no end of bother, throw it in the bin and run a new fuel pipe sender to the lift pump, the tank pick up top also rots out, easy to get to as under a plate under boot carpet.
Even when you run the 200 out of fuel they self bleed quite easily on the starter, not that I would be that stupid you understand!