citroen dispatch 2001 not starting?

hi there, can anybody please throw any suggestions at this problem as im struggling as what to do next.
A couple of week ago as i was going up a hill my dispatch just seemed to loose all power in terms of fuel going to the engine, i had no accelleration came to a stop and the engine cut out. i tried to start it again and although it didnt straight away after a couple of mins it started, i didnt really think much of it at the time.

since then this problem has become more frequent and really came to a head yesterday when i stopped for a brew and turned the engine off.

when i tried to start it, it was turning over like it wanted to start but wouldnt. i rang rac and he said the fuel pump was working so he didnt no, might be immobaliser or crack sensor. althought i have since learnt that there is a 2nd fuel pump.

so after a £100 tow truck ride home it went to a mates garage but was too busy to look so i started playing myself. I thought the water level look a little low so i put a bit of water in and started wiggling and unclipping and reatching various plugs in the engine bay and then it started??

they attached the computer diagnostics and it came up with all sorts of faults but iv been told it would if i took a plug off. my guesses are a loose wire somewhere, an earthing problem (but iv been told they dont think its that), a relay, or a sensor somewhere in the fuel line, or possibly a fuel pump but im sure its an intermitten falut so i cant understand why a pump would work sometimes and not others, surly once its gone its gone?

so the vans running at the moment i have it at home but am scared to drive it a long way incase it dies again, has anybody experienced similar problems or have any idea as to what to do 1st considering i dont have loads of money to throw at it.

any help at all will be greatly appreciated, thank you, rob.