94 7.3 powerstroke headgasket? HELP

[Judspud]

I bought a 1994 powerstroke from a guy with a "possible headgasket problem". When I got there and test drove it, there was hardly any water in the oil, just enough as if it had condensation from sitting for 2 months. The truck ran awsome with no missing and plenty of power. So I handed him some cash and changed the oil because I was gonna drive it 20miles home. So I was cruising along at about 60mph, there was one miss, another miss, two consecutive misses and the motor shut off, the oil was pretty milky now. (temperature guage never went passed 1/4 and coolant was at the same level as when I left his house) So I thought maybe it ran out of fuel because I would let it sit for 5-10min then it would fire up, go to 500rpm, then stop running. I had the guy bring me 10gal of fuel and put 5gal in each tank. Still did the same thing so we checked fuel pressue at the bleeder, good fuel pressure. We checked the fuel filter thinking it may be clogged, filter looked brand new. So after trying to get it fired up with the pedal mashed to the floor or just idling, all of a sudden it fired up with the pedal to the floor so I revved it out a little to keep it running. Walla, ran perfect with no misses and plenty of power. I wnet one my way again and about 7mi down the road it did the same thing. After about 45 min it fired right up again. By this time I had called a tow truck and they were in route. I got it towed to my house and after the tow truck driver dropped it in front of my house it fired right up. I backed it into the driveway. I got up this morning, went outside and it fired right up again so I pulled it in the garage to vaccum the interior and all that. I went to fire it up to pull it into the sideyard where I plan to change the headgasket on it and it wouldn't fire up.

The guy that sold it to me says he thinks with the water in the oil and when the oil heats up and looses viscosity the oil around the injectors is cavitating. Causeing the injectors to shut off just as if you were low on oil.

I have until this Sunday to fix this thing because I have to get to work/home about 200 miles away.

I would REALLY appreciate it if somebody that has possibly had this exact problem or has heard of this problem would give me some good leads in a direction to go about figuring this out.

Thank you, Jud