THE_CARNEYS

We have an 01 Blazer LT,4X4,4 dr,auto trans and a 4.3. The fuel pump in it now iz a 1 yr old TYC brand iz SOMETIMES makin a louder and different noise than it was until a week or so ago when this started. Also the Blazer WILL NOT start unless it is sitting on level ground and iz hocked to jumper cables and another vehicles battery and even then sometimez it will not start. When it does start tho it will sit and idle perfectly until i get in and start down a small hill in our driveway. When i start down the hill with the tranny in neutral and the tach at around 3000 rpm it will stall out every time (i've done this a few timez) no joke, seriously!! We have near a quarter tank of gas in it so fuel runnin away from the pick up izn't the prob. Checked the fuel pressure it starts out @ around 50 psi with the switch at the on position & from what i've discovered 50 psi iz where it should be. So have you ever heard of anything running like this and if so what was the cause pleaze?
God bless!!