1999 Ford E-Series Van runs horriable

As far as the "feels like a gas engine misfire" this is mostlikely a bad injector. What worries me, is you describe no power. These have from time to time been known for turbos going. Do you have oil comming out of your exaust? How does this engine start? Long cranking? The glowplugs fire this engine for start up, then compression fires the cylinders from there. There are a numerous amount of causes for what you describe. Injectors, and low compression most common for the misfire you feel, and turbo being common for low power.

There is an injector driver, located above the intake manifold, towards front of engine, on driver side. Has an electrical plug on top. This may be intermittantly failing. It controls oil flow to your injectors. Very common part to go bad, and will also give symptoms you describe. It is a bit tricky to change, as it is 3 pieces. And in a bad place. Take your time, and dont get mad at it. Should take about 45min to an hr first time around.