;86 Westy

Ok, I've spent the entire week on this.   Tomorrow I have to drive
from Winnipeg back to Calgary and I don't know if I will make it.  I
believe I have two problems...and I can't find either one.

Problem 1
Van hesitates at cruising speed or very light throttle.  Just a small
surge, almost like lugging the engine in too high a gear.
        -Changed fuel filters
        -visually inspected fuel system

Problem 2
When driving over bumps, or sometimes by itself, the van tach will
drop to zero.  Obviously this is an electrical problem.
        -Checked every wire I could get my hands on, wiggled them while the
engine was running, from the ignition switch to the distributor.  I
cannot make the problem occur by myself
        -redid all the grounds I could get my hands on.  Ran through the
van with an Ohm meter...resistance is zero or near zero in all cases

What do I do next?  Besides slice my wrists and be done with the
problem :-)

Thanks
Gregor