Help: Cuts Out In Water

when i go through a puddle really quick, or through avg depth water the rover v8 seems to cut out and nearly die, it seems liek it gets an electrical shortage but i am not sure what it is. i have replaced teh dissy cap, leavd etc and it stil seems to have this problem.. does any one know what this could be? or have seemd to have teh same problem?

any help much appreciated. cheers