This truck has 300,000 miles, if i plug it up at night it starts fine. if not pluged up i will crank until it kills batteries end up shooting starting fluid in it before it will start. once it fires up, it runns rough until warm then great like nothings wrong. If it is plugged up it will start right up and run perfect, any help. Thanks

 

Can be a number of things, bad glow plugs and relay, but that does not cause rough running.

Low oil pressure on the High Pressure sides.
Bad ICP, IPR Sensors. Which can cause rough engine operation. The easiest way to test this is with an good OBDII such as the snap on verus. But it can also be the engine is getting tired.. But Im not gonna bet my money on that.

 

Glow plugs replaced last oct. And it made no difference. Harness and relay were good. I keep getting people saying injectors are sticking but it sure seems to run great after getting started. I noticed today after starting that after sitting at an idle for a few min it went to high idle, i tapped brake pedal and it instantly idled down to normal.

 

My truck (Dodge) has a programmed PCM for high idle, and yours may too I also believe if the E brake is depreesed it will allow it to go into high idle. Sticking injectors dont cause no starts on a cold start, they cause rough running untill warm, but they would not cause a no start. Its difficult to diagnose your problem but try unpluging the sensor on the driver side next to the valve cover on the upper front of the engine before you start it and see if it makes a differnece in how it starts if not I would lean torwards the HPOP. Hows the blow by?