4000q has an "episode"

[Russ Maki]

My '87 4000 quat had an odd episode over the weekend. I had just got done
replacing the right E-brake cable and pull rod (twisted off at a rusty point
when I was trying to install the cable). I fired it up and it acted as
though the wiring to the differential pressure regulator was disconnected --
hard to keep it running, some backfiring, etc. Shortly thereafter I noticed
that the trip computer was shutting down whenever I'd turn the ignition key
from "off" to "on." Shutting down, as in the clock reset to Zero with a
blinking hour numeral.

I went out to the car Sunday morning with my Bentley and multimeter, and the
thing fired up and idled smoothly, with no symptom of the prior trouble. I
scratched my head a bit and took it out for an extended test drive.

About 8 miles into the circuit, I experienced a sudden and extreme loss of
power. I finally disengaged the clutch and the car stalled immediately. I
let out the clutch again (at about 45 mph) and in a fraction of a second the
car lurched and resumed running smoothly. After that it purred for another
20 miles.

The fuel pump relay is brand new. The fuel pump is a salvage part but seems
pretty quiet -- although I can hear it hum when I turn the ignition on, even
when the car was running poorly. The on/off nature of the condition has me
thinking switch or relay, but I'm pretty much stumped. I don't want to use
the car for my 40-mile second shift commute with this hanging over my head.
Does anyody have any suggestions?

Thanks,
Russ Maki
Ixonia, Wis