I just replaced the injectors from the old style to the new MFI injectors. I changed them because we thought it might have been the cause of the misfire condition in multiple cylinders and broke 2 injectors in the process of looking at them (long story). So the new assembly is in the truck but seems to still be misfiring. After we changed the part we started the engine and it ran great for 2 min, and then seemed to be starving for fuel after that. Took it for a drive and had literally no power. Seemed to have barely made it back to the driveway. Could it be possible one of the nozzles slipped out of the cylinder? I did notice #5 a bit more loose when it was installed than the other 5. Is this the problem, or is it possible the misfire condition all together is a bad fuel pump. Plan on a fuel pressure test tomorrow but wanted some help troubleshooting this problem.
Get the fuel pressure first. Then you will know if there is a problem with the regulator or the fuel pump. Once you have eliminated these as a possibility, you can look at specific injectors for problems. Low power GENERALLY points to a fuel pressure/regulator problem.
I think these trucks have seperate coil packs. Have you checked the coils to make sure they are OK? Check the resistance of the prmary winding and the resistance between the primary and secondary winding against what it says in your manual.