I own a 95 f150 with a 4.9L 5 spd. If the truck sits for more then a few hours, I turn the key and my truck will just stummble and at times die. Once I turn the key again it fires right up. I'm guessing that it could be the fuel pump because I only use the front tank. My rear pump is not running well at all. Or my other guess is the fuel regulator. If so, how do I test this?

 

With the engine running pull the vacuum line from the regulator and cap it with your finger. If the idle picks up it's good. Also if it's bad then sometimes gas will come out of it when you pull the line.

 

sounds like your rear pump, pressure regulator, and replace the fuel filter too

 

I know its not the rear pump. It doesn't prime at all. I only use the front tank. I tested the fuel regulator and thats not it. Now i'm going to drop the front tank. Seems like i'm replacing the pump. Filter is fine. Once the truck is running its fine.