Well I went out and bought myself a torque wrench and torqued the bolts all down. I just guessed before, looks like I actually over-torqued them though. All the bolts where just over 100in-lbs already. Looks like I'll have to look elsewhere for the cause of this problem

If it was the fuel pump, I would get surging right? Or could the fuel pump be starting to fail and not push enough fuel to the injectors?