'92 Ford F-350, 7.3L IDI, 295,000 kms.

Excuse the long story but I feel it's necessary to describe what's going on properly.

I have owned the truck for about four months now without any issues. In that time I have changed the oil and the oil, air, and fuel filters twice each. I always run Sunoco Gold Diesel from the same [relatively new] station and usually run two-cycle pre-mix oil in the fuel as well.

About three weeks ago I filled both tanks, got about half way through the front tank when it started running poorly in certain situations. It would start, and for the most part run fine except occasional very rough idle for 3-5 seconds, but almost always when putting it into drive or reverse at low speeds with no or little throttle input it would run like garbage and sound like a derby car. After getting it above 1000rpm or so it would clear up and run fine.

So, I decided to try and run on the rear tank to see if it made a difference and to my surprise it ran perfectly fine. So until I figured I would just run on the rear tank until I had time to investigate what's wrong with the front tank. It ran just fine on the rear tank for two weeks, about 2,500 kms and maybe three or four tanks of diesel - no problem at all.

Truck got parked last Monday while I was away for a week. Got back yesterday and into my truck to drive home, started up just fine but immediately had the exact same running issues as it did on the front tank, except on the rear tank which was half full. Ran it down to 1/4 to see if it would clear up, no change. Filled it with fresh diesel this morning and 500 mL of Power Service, no change. So I bought a new fuel filter, filled it with ATF and put that on, ran kinda better for a few minutes then back to the same problem again.

Took it out tonight and went to pick up a girl. Shut it off while we went to Tim Hortons for 10-15 minutes. Got back in the truck and for the first time ever it refuses to start. Made 2-3 attempts cranking of about 10 seconds each, waiting for glow plugs etc. and blipping the throttle slightly then it finally starts and runs fine, strange... So we go out to this spot in a field and I make the mistake of shutting the truck off. Then about an hour later I go to start it again and this time it absolutely refuses. I tried and tried and tried and no luck. Had the girl crank it over while I depressed the check valve on top of the filter and lots of pressure. Checked over everything I could visually with only a cell phone light, jiggled every electrical connection I could find and really couldn't find anything at all. So I'm just about ready to give up and abandon it in this field when I decide to try one more time and amazingly it starts.

So it's running but generally the same symptoms as before. Occasional poor idle, running very rough at low speeds forward and reverse (especially reverse it seems) etc. Dropped her off and headed home. Now getting strange unexpected bursts of power under light acceleration and even when cruising at 80km/h (50mph) like 3-5 seconds of giving it 25% more throttle, but I'm not. Then other times it will fall on it's face when accelerating like it's running out of fuel, I'll keep pushing the pedal down and it will accelerate very slowly or not at all. Yet I'll let go of the pedal and it will come back down and idle just fine then usually clear up. Nonetheless it got me home fine, could have been a lot worse.

So, the truck is parked in front of my shop now ready for me to try and figure out what's wrong in the morning. This is my second Ford truck but my first diesel so I'm not too sure what I should be checking first. It's my daily driver and I especially need it to get into work tomorrow afternoon so I would really appreciate any help or advice you guys might have. To make matters worse I broke the shift linkage on my Porsche 924 yesterday so I don't have a vehicle at all if I don't get this thing fixed, I'm thinking it's not going to start at all.

Thanks in advance