Ok to make things simple,
if you think it is a fuel pressure problem from the filter or the pump
turn the key and wait until it stops from building inital pressure then turn it off and do it again 3 times total, if it starts right up then you might have a pressure problem,
If not then you need to look at otehr areas,
what maintance have you done since owning it?
and most important what year is the car???????????//