95, 2.2 surging

Let's say I'm driving along with the needle pointed straight at 40 mph, to take an example. The car will sometimes not drive steadily. Can't decide if I'm getting little bursts of speed or if the opposite is happening and I'm loosing bit and pieces of power. Usually it's subtle, thought definately noticeable, but sometimes you'll get a bucking where you wonder if the thing is going to stall.

Happens at other speeds as well. Not when idling (so far) and not when slowing down of course. And I haven't noticed it while accelerating...yet.

What should I be checking?

Am in the process of changing the fuel filter. 50,000 miles overdue. Just have to get that damn clip to work right...

Let's say I'm driving along with the needle pointed straight at 40 mph, to take an example. The car will sometimes not drive steadily. Can't decide if I'm getting little bursts of speed or if the opposite is happening and I'm loosing bit and pieces of power. Usually it's subtle, thought definately noticeable, but sometimes you'll get a bucking where you wonder if the thing is going to stall.

Happens at other speeds as well. Not when idling (so far) and not when slowing down of course. And I haven't noticed it while accelerating...yet.

What should I be checking?

Am in the process of changing the fuel filter. 50,000 miles overdue. Just have to get that damn clip to work right...

I have been fighting this on my wifes 99 LS for years.
Replaced Alternator
Replaced Coil packs (both)
Replaced plug wires
Replaced fuel filter
Replaced battery cables (pos/neg both corroded)

hers is when holding steady at 2000 rpms (or trying to)

HERE IS A HUGE CLUE: Only exhibits after hitting a bump/pothole/etc. When it starts, CRUISE CONTROL NO LONGER WORKS, sometimes the windows will no longer roll down, and the blinkers act sporadically-if not totally fail.
This has lead me to a central ground somewhere that is NO LONGER maintaining contact.

DOES ANYONE HAVE A SCHEMATIC addressing where all these systems might share a common ground????:banghead:

haynes manual has schematics in the back...