It all started with a code for Cyl.#8 Misfire. I checked all of the usual stuff and found that I had very little fuel psi (5psi), so I replaced the injectors. The misfire code went away immediately after replacing injectors, but I still had low power and high fuel consumption. A friend pointed out that my exhaust was shooting flames shortly after that. Tested my Cat and found that it was plugged (probably from all the excess fuel getting pushed through it). So I cut off the Cat and found that it gave me slightly more power but still not like it should have and still high fuel consumption. Along with the normal "heater control"code from removing the Cat, i now have a "too lean" code. I figured that was from the intense heat from the clogged Cat so I have now replaced the front O2 sensor and the "too lean" code is gone. To add to this, the other day I had just fueled the truck up and it started acting as if the fuel pump was dying. It chugged and died out at every turn and about 4 more times within approximately 1 mile. The truck sat for two days and now seems to be running okay besides having the low power issue still. And my updated fuel psi is 45psi and holds..(spec for the 4.7l is in the high 50s though I believe). I almost forgot, the engines idle ever since I've bought the truck has been 400-500, and when reved up, will quickly drop down and act as if it is going to chug out and die, this has been happening ever since I bought the vehicle.
Does anyone have any ideas on what my issue could be? Should I still replace fuel pump like I had planned? Thankyou!

 

Have you considered replacing or trouble shooting the TPS and IAC valve?

 

If your fuel pressure is 45 and the spec is mid 50's. Sounds like a fuel pump going bad. Most vehicles have a fuel pressure range. Ie 48-52. I would double check the exact spec, before I changed the pump.

 

No, I hadnt even thought about the TPS or IAC valve. I will definitely take a look into those!

And I will have to double check the fuel pressure spec for my engine..