2001 Camaro v6 127,00 miles 5-speed

My car has been running really rough. Very choppy when going up hills or accelerating hard. I have code P0300. I have changed the following parts: all sparkplugs and wires, air filter, fuel filter ( 1 1/2 years ago), and cleaned the MAF sensor.

Yesterday, i checked the fuel pressure. the readings were:
key on: 48, then drops to 44 and holds for 5 min
idle: 42
@ 2000 rpm: 40-42.

Are these pressures normal?
If no, what could be the problem?

 

fuel pressure seems ok. have a look here and see if any of this helps. https://camaroforums.com/forum/gener...e-p0300-53531/

 

My dad says fuel pressure should be between 52 and 60, Is he correct

 

Sounds like something wrong with the transmission if its only under hard load. Is the clutch ok?

 

50 to 60 on the 3.8 is normal so it is a little low.

 

at what pressure is it necessary to replace the pump?

 

for the sake of piece with dad i would consider replacing the fuel pump. although it could be the fuel pressure regulator. did you try unplugging the fuel pressure regulator when you were doing the test to see if it changed.

 

craby. I did not unplug the reg. Did not know to do that. I will try that soon. thanks