My car has problems starting when its parked on a slant, or a hill, or in the mornings when its really cold.
I replaced the fuel filter and its seems to drive more smooth now, but still I have the problems. So I thought that it could be the results of a bad pressure regulator, cause when I crimp the pressure line behind the regulator, nothing happens. (im not sure if nothing is supposed to happen tho!). Any suggestions, I was thinking of getting an AEM type with the gauge attached to it.

Not too useful for your application, IMO a waste unless its going to cost you less than an OEM replacement, which is what I would recommend.