[urq] Stumbling

[Thatcher Hubbard]

My problem lingers, though I haven't been aggressively trying to fix
it.  But I noticed a couple more things that make me wonder if it's
not an electronic problem.

First, when the problem happens, the revs drop, but I can hear the
engine still firing.  But, the tach drops to zero and then bounces
back up again right away.  It will do it when I'm off the throttle
(coasting) too.

Second, which sensor is it that can cause the fuel pump to cut out? 
The MAP sensor in the ECU?