Persistent hard/no start

[Ghostdriver86]

I have a 95 F350 5-spd manual that has had a persistent and progressive hard start problem since shortly after I bought it 3 years ago with 144000 miles on it. It has 168000 miles on it now, and I have put over $8000 into the truck just trying to fix the hard start, replacing all the usual suspects (fuel bowl heater, plugs, harnesses, injectors, relays, I think there was a control module in there somewhere, etc.) It gets better for a while, then starts getting cranky again, and gets worse. I now have to use the block heater all the time if the truck sits for more than a few hours after shutting it off, even when it is 60 degrees out or more. Without the block heater, it cranks, but will not start, lots of white smoke. If is is warm, it starts right up. Once I get her going, she runs like a top, making great hp and very good fuel mileage. I have finally found a mechanic that is good, reliable, and that I like, and he just diagnosed it, and all operating systems came up within specs. He says I may have a computer problem, and that a dealer would have the equipment to diagnose it. Nobody seems to want to talk about computer issues. Anybody know what I may be up against?

[sldghamr]

did you try a compression test??

[mschn99]

pull your fuel filter out and look for some "tar" like stuff at the bottom of the bowl...good chance your injector o rings may need to be replaced....

[Ghostdriver86]

Fuel filter is checked and/or replaced every 3000 miles at the oil change, nothing abnormal. Injectors and rings were replaced about a year ago, no change. I don't think it has had a compression test recently, but the results at the first emissions test 2 1/2 years ago showed exceptionally good compression, especially given the age of the truck. I'll recheck it. Thanks!