Jeep: 89 XJ 4L Automatic---Hiccup every 8 miles cruising on highway

New to JEEPS"
Just bought it, drove it home 50 kilometers and now sorting out how it works
and what needs fixing.
Highway cruising, every 10 k or so the '89 XJ 4L Automatic Cherokee Limited
experiences a momentary power or
driveline hiccup, it's as if the key was turned from ON to OFF then ON
again., resuming normal power. It happens
so fast that you can feel it but don't have time to scan the Instrument
panel to see if the tach. needle dropped or not.

It had quit on the previous owner, towed to the dealer and they replaced the
crank position sensor, and fuel pump.
Just wondering if there is a driving computer Oxygen sensor timer to hunt
for leaner mixture setting and maybe
a bad sensor is bouncing it back to cold engine fuel mixture setting. Maybe
EGR Valve?

Just replaced the ignition key ( jammed tumbler) yesterday, so with battery
disconnected for a couple of hours it'll have a
computer reset, and that may or may not have an effect on the hiccups?

Acknowledge that the AW4 Transmission fluid & filter needs changing (light
brown), transmission linkage
(crumbled plastic bushing on linkage at shifter end) may be affecting shift
down on hills -- it won't do it on it's own.
It shifts up fine but will not downshift on it's own when accelerating on a
hill.

Could compromised dielectric strength of dirty and cooked tranny oil be
shorting shifting solenoids and causing bands to
momentarily release then grab again?

Any other ideas?

Spud
__________________
Usta-been a spud farmer, before that
a dairy farmer, before that, a Mechanical Technician.

Thanks Mike,
I've been going around the underside and innerpanels with Rust Check,
rebonding grounds where I see them, never thought of the engine ground
straps though.

Spud


"Mike Romain" <ca> wrote in message
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