Fuel problem!

Hi I have a 2003 Chevy Tahoe 5.3L w/ 85000mi. For sometime the truck wont start when the gauge reflects just below 1/4 tank. Recently I was driving on the highway and the truck stalled. I attempted to start it and had no problems. The other day I left work and could not get it to start. I drifted the truck forward were it was facing up a small grade, and it started right up; However was idling strangely. Ireplaced the fuel pump, and now it won't start. When I turn the key forward without attempting to start i. I can hear the pump engaging which leads me to believe the pump is fine. I disconnected the inlet line to the fuel filter and attempted to start the fuel began to drip out not surge out like I expected. What do you hink my next step is. I'm considering the relay.