Guys, i have just replaced my fuel pump in the truck. now the truck shakes/studders in parking lots and is harder to start. It is an 01 and i just got done changing the IMG not to long ago, a week after that the fuel pump just died. I got a fuel pressure test kit and mine is at 52psi and drops into the high 40s upon acceleration of the engine. The crazy thing is after I shut the truck off to check leak down, the pressure goes up to about 60 and hold there for many minutes. Could a fuel filter cause this type of issue? I was expecting to see it go down at some rate, but not rise.

 

Change the fuel filter. I don't know if it'll help your problem but they should engrave on the fuel pumps "when you replace this put a new filter in while you're at it". There's a good chance yours is plugged and if so the new pump will last 3 months. As for the fuel pressure behavior.... It's not quite as abnormal as you think. Put the pressure gauge on it and turn the truck on for a few seconds, turn it off, turn it on again without starting it and check the pressure. Post it (I'm just curious) Normally you check fuel pressure without the truck running. When you start the truck your fuel pressure regulator operates according to engine vacuum so when you look at it running you're seeing both the fuel pump and regulator in action. It'll drop when you hit the gas and should stabilize at a steady throttle position. When you turn the truck off your pump should run for 3 more seconds before shutting off. Since the motor is stopped and not generating vacuum the regulator will let the pressure rise to a point. 60 is just about right and the holding steady is what you want to see. Post the pressure with the engine off and *replace that filter* first thing.

 

First, thanks for your help, i went back out and replaced my fuel filter. Filter was clogged up pretty bad, i couldnt blow thru it. Afterwards, the pressure is the same as it was before running at 55psi. Off state is 56-58 depending on the angle that im holding the gauge. Also i notice that the three seconds that the pump is on the pressure is about 63 psi then drops down to 58 after the three second inital turn on.

 

My best friend replaced his pump on his 2000, replaced it again 3 months later 'cuz he didn't replace the filter. Mine was plugged changing it after seeing what he did. Your pressures all seem in proper range for the truck to run well.
I can't see changing a pump being the cause of the problems you have. <thinking out loud> Assuming the truck ran well before you did the intake gaskets.... Those SES lights are annoying to look at but I wish your engine light was on to offer a clue. If you left an electrical connector off you'd have a check engine light.
Does the truck run differently warm or cold? (run better/worse when the computer goes into closed loop)
If you have manual heater controls do the doors seem to work right? (sign of a vacuum line off)
When you had the intake off did you happen to look into the ports? One side clean, one side carboned? (signs of the leaky spider which can only get worse)
Did you take the EGR valve off? Carboned on the end? Maybe you should look at it now... A bit of carbon broke loose and got into it holding it partly open? That'll mess up starting, idle definitely and low speed maybe?
Make sure all your electrical connectors are snapped on well and it's not an intermittent connection problem.
Looking at another thread I saw another possibility, make sure the plug wires are right. #1 & 3 are easy to reverse.
Oh, and you could try disconnecting the battery for 10 minutes and resetting the computer. If, by changing the fuel pressure, the truck needs to use a different set of cells (fuel curve) that would reset it and make it relearn. But not likely, it's a small change if any and the computer should be able to do it on its own (but a free outside possibility to try).