Rough idle / smoke

[floorboy]

I stopped at a light today and felt (had the radio turned up) my truck idleing rough. By the time I turned the radio down it came out of it but I looked in the mirror and noticed a BIG puff of smoke. The whole thing lasted maybe 3 seconds and it never did it the rest of the day. The truck had been running for approximately 10 minutes at town speeds but was in a heated garage all night. Something going out? Injector?? Truck has 309,000 and is stock other than a mild tune. It has never left me standing in all the miles even through the cps and tranny issues I've had. I do a lot of long trips with it and would rather not be stranded in -20 degrees this winter. What could it be?? Thanks.

[floorboy]

Anybody?? Ideas??

[~CrazyDiesel~]

What color was the smoke? Has the fuel pump ever been replaced? Fuel pressure could have dropped out momentarily, or the IPR could have stuck closed and ICP spiked. Any number of things.