I think somethings wrong?

[THEFERMANATOR]

Also 7.3's have the high pressure oil pump that does seem to fail quite a bit after 100K miles or so. On a truck they aren't that bad to change, but have no idea about a van. I do know the high pressure oil sensor on them is pretty critical, and I have heard about quite a few high milage units getting eratic or poor readings from it which in turn causes the high pressure oil pressure to fluctuate alot and cause poor driveability. Alot of people don't know it, but you should also drain and flush out the high pressure oil pump reservoir from time to time to prevent sludging of the high pressure oil system and costly repairs. I'm not really up to par on the vans as all of my research was into trucks as I came VERY close to buying a 7.3L EXCURSION before I DURAMAXED my BURB. The 7.3L is a good workhorse engine, but without spending a TON of money it will never be a rocket.

Any way you look at it, you will be hard pressed to break 400HP out of a 7.3L and that is doing a high pressure oil pump, injectors, turbo, and in your case adding an intercooler or water meth injection. If you want power, find a DURAMAX van and retrofit an ALLISON into it(the vans are REALLY held back ALOT by the weak 4L80E trans). Or find a 6.0L van and put head studs and delete the emissions crap then tune it. As for a 7.3L tuner, the only one I would use is DPTUNER.

And for your trans, get it rebuilt and make sure you do the valve body in it as FORDS mushbox valve body design really doesn't help the 4R100 live very well. FORD and a few other companies have a modified valve body for them, I'm not sure about which shift kits to put in them to firm things up. And I believe the 6.0L torqshift torque converter is a good cheap upgrade for the 7.3 as well.