7.3 driving me crazy

Where do i start.
Bought a f250 2004 7.3 4x4 extra truck with 170000 miles having just sold a 2006 crew with 20000 miles.
Buying price is cheap(well cheap in Australia,sold my 2006 with 40000km's for $88000)
As i'm due to pick up the 04 the seller tells me there is a problem with it and he has it booked into Ford.he tells me the fault is running on 1 bank occassionally)I do some research and figure i can fix this(UVCH's,IDM??)
Buy the truck even cheaper.
2000 mile from home,no parts available without a weeks wait.
Could not get the truck to fault when i test drove it 20 miles.
The truck is now mine.Driving real well,then rough for 5 seconds,check engine light,then clears and continues to drive well.
Pulled and checked UVCH's plugs and connections all seemed good.Ohmed wiring harness from IDM.All readings within spec.After 20 mile on highway down to 1 bank.Drivers side exhaust cold.
Ordered UVCH's,IDM and the oil sender that fits to the Passenger side(remember we sit on the other side)head front area.Is it the ICP?
After sitting for a while it will start and drive well then the 1 bank running starts.Normally once it starts it continues.
Replaced UVCH,s no success,IDM no success,ICP sensor no success.
Replaced oil,oil filter and fuel filter,no success.
Mechanic's recommendation was HPOP so replaced with very low K's HPOP.Still the same fault.Connected fuel pressure gauge at filter and had constant 60 PSI.Fuel pump looks new.
No oil from injector drains drivers side when running,occasionally injector cylinder 3 had oil.
Finally found that when the wiring harness in the valley was pulled a certain way engine increased decreased.Has to be the problem.replaced entire harness from large plug on top of passenger rocker cover.Engine runs smooth and all drivers injectors have oil.I'm thinking we have won.
Now to the current fault and i'm thinking it maybe something i've created.
It is now very hard to start,cranking 6-7 seconds,sometimes longer,seems to start easier the longer it is left sit.It then idles and it varies between 10 to 1 minute,then a detectable miss that progressively gets worse until stalling.
Fuel pressure at filter is good.Air has been purged from fuel,return at filter disconnected and run into a bucket.Pulled oil feed to drivers injectors and got about 100 ml's of oil with 2 cranks.
Crank sensor has also been changed.Pulled the HPOP out again and refitted the original.4 people have spent 3 solid days under the bonnet.
There are probably things we have done but forgotten to mention.
Sorry for the huge post but i'm at a complete loss.