my truck starts running really rough randomly, shuts off battery light comes on, has a hard time cranking over and will run rough and clear up and drive fine for awhile, only when the truck decides to shut off is when the cranking has a hard time, thinking its a injector, just replaced #8 4 months ago but i noticed alot of white smoke when it first starts. pretty sure its injectors but i dont wanna tear the thing apart if its something simple

 

Intermittent rough running and stalling isn't likely to be caused by injectors. I'd guess electrical issue. The rough running and stalling could be CPS related. Sensors do fail, but at the age these trucks are, wiring failures are becoming way more likely. The CPS wouldn't explain the slow cranking and low voltage behavior though. That would have to be tied to main power somehow. Bad battery connections and poor grounding are possible as well as the cables themselves. Could also be a problem in one of the fuse panels or relays too. I'd suggest getting a way scan for codes and monitor engine PID's for starters. You can read through the information about Forscan up in the stickies section for the cheapest and simplest way to do that. I'd also suggest a fuel pressure test. There is a simple method listed in the tech section if you'd like to read that as well.

 

I'm no where near as knowledgeable as others here but most of my issues were with crank no start and stalling. When stalling it was like I cut the key, sometimes predicated with a lag/lug in rpms, clunk or two then would die or come back, luck of the draw. Basically everything worked great until it didn't, sometimes with rough running's other times outa nowhere, except for the constant anticipation of the next stall.
In my case it was the ICP/IPR and CPS. My IPR was difficult to see at first because it would idle and sound great while in park just stall out while moving in gear. If you do decide to replace the IPR I highly suggest getting a Ford/Motorcraft from dealer, RiffRaff, or other reputable source, and if any of the other sensors are already replaced with anything other then Ford I would suggest replacing them as well. The other reason I overlooked IPR until the end was I replaced it about 5-7k miles ago, but that seems to be the culprit.

The random hard cranking is odd, every start is a hard crank or just when she starts acting up? I was surprised when I had a shower of sparks come from the right front wheel well one day when starting and discovered that the main feed to starter was nowhere near secured. Long story short, I needed to get a new starter. Could you have a loose connection at the starter?

There is my two cents, fresh from the inter-webs. Hope that helps.

 

A lot of white smoke on first startup could mean several different things. Low compression is the first thing that comes to my mind because the diesel engine relies upon it's very high compression ratio to heat the air in the combustion chambers up to the ignition thresh hold for the fuel being injected. Low compression will cause the engine to over-fuel because it's struggling to run when it's cold. As the engine warms, it becomes easier for the compression alone to bring the air in the combustion chamber up to the ignition point without having the cold iron of the engine block suck all the BTUs out before it has a chance to fire that injected fuel.