My 97 6.5 have a surging problem, the rpms will go up for a couple seconds and then back to normal for a couple minutes then back up for a couple seconds etc etc when idling, when driving ill be driving along like normal and then the truck will act like I floored it when I didn't do anything but it only lasts for a couple seconds then goes back to normal and it keeps doing this and I have no idea why, I'm not throwing any codes or anything, could it be a malfunctioning injector/injectors? Or am I completely wrong? Please I'm in dire need of help on this, I desperately need this truck 100% for work purposes

 

Runaway sounds like a PMD as the injector only pass what fuel is supplied to them from the IP which is controled by the PMD

 

Flight systems PMD failure or fuel solenoid hanging in the IP.

Try the PMD first with a remote mount kit since it is much easier and cheaper than an IP.

 

I would assume it's the pmd, but would that also cause hard starting? Almost like its starving for fuel then gets a big burst of fuel and finally fires?

 

The PMD can cause hard starting but the IP fuel solenoid can cause that as well.

Another common reason for hard starting is a leak from the fuel heater or water in fuel sensor O-rings in the filter housing.

When they leak air is let in to take the place of lost fuel and hard starts occur after an extended sitting period.