Hesitation, cuts out, dies

[bjxj]

87 renix cherokee, 4.0 auto.
Started to notice a slight hesitation when first accelerating a couple days ago. Nothing real bad. Then drove home from work, parked it couple hours, when I left to pick up kids from school, hesitation and engine cut out was so bad I could not drive it on the highway. Starts and idles fine, just cuts out badly while driving. First thought was fuel pump or filter, so replaced both, no change. Checked MAP sensor, bad readings, replaced it, and now seems to be worse. Started it to let it idle, it ran for a few seconds and died. Starts right back up, but dies intermittently at times. Checked coil, tested good. Any advice or recommendations would be greatly appreciated. Thanks.
Also... after fuel pump and filter replaced, I test drove around block, started out good, could tell it was not completely fixed, but not bad, but by the time I got back home, it was consistently cutting out and sputtering. Still idles fine and revs fine in park.

[4.3LXJ]

Does it happen only at operating temperature?

[bjxj]

Yes mostly, my test drive was good while it was cold, but when it warmed up, was terrible again.

[4.3LXJ]

Long time since your Oxygen Sensor was replaced?

[bjxj]

O2 sensor is not connected, never has been since I have the xj.

[4.3LXJ]

Probably ought to connect it up with a good one. When your engine gets up to temp it relies on the O2 sensor for information. If it doesn't have it the fuel air mixture could be anything. In this case, probably too lean

[tommy guns]

Check all vacuum lines.Sounds like a vacuum leak.

[Infidel Edition]

My '89 RENIX has what may be similar issues ~ though far less frequent.

1st time I thought it was due to heat issue. I had driven it hard for around 1000 miles at high speeds in hot summer heat. Then at a slow point, it acted like it was "out of gas" even though it was full. = sputtered and died. would restart, but sputter and die as soon as I tried to drive again. Someone suggested it was the CPS overheating... apparently known issue to some. After it sat for 20 minutes, it was good to go.

2nd time I though maybe I had gotten bad fuel. Maybe water in the gas :bang::bang: but the issue was almost identical except for it was WAY COLD outside and it happened at highway speeds.

* it's happened may be 4 or 5 times in the last 5 months. But I only drive it once or twice a week. And both of the above times were on longer (150+ mile trips). Around town is fine.

I've narrowed it down to a few things that I still need to check (once I have warmer weather to work on it).
I've replaced most of my main power wiring (+ and - from battery to x, y, and z) with better gauge. and cleaned the connection points.
But it was recently suggested that there is a bad ground (known issue) under the dash.
1 = driver side under the dash by the kick plate ~ look above the hood release ~ make a "jumper wire" (not sure what else to call it) with 10 gauge or bigger from that current ground to a spot 10" closer to the firewall. There's a bolt that has a better ground to the body there. ** use search and you can find the topic here.

2 = the ICM is solid-state and doesn't go bad (so I'm told), but the connections under it get corroded over time. So pull it and clean them with a nail file or sandpaper and use some electric grease.

3 = bad computer. I'm going to try all the rest first, but a friend said when the RENIX computer starts to fail, it'll act like mine does.
BTW, RENIX computer is only $100 +/- at rockauto.com

THUS~
I'd start with the O2 sensor. The computer calculates fuel based on the O2. ----not sure how you've been running without it??? you are fuel injection right?
---the computer uses these #'s and others to tell the injectors how much to inject and when = could act like "out of gas" or "bad fuel pump"

Also look at checking your wiring connections
- remove and clean the batter cables AT BOTH ENDS.
- the ICM clean and electric grease.
- the ground wire under the dash...
:flameon: don't shock yourself :rolleye0012:

Then, if you haven't replaced the CPS (pain in the :ass:) between the block and the firewall on the drivers side. But can be done with patients and a bunch of extensions in 30 minutes (my time and I'm a nob!).

Also Fuel Injectors clean?

[Infidel Edition]

Here's the link to the threads I posted in relation to my 2 initial hesitation issues + the 1 on the wiring upgrade:

http://www.xjtalk.com/showthread.php?t=16518

http://www.xjtalk.com/showthread.php?t=15817

http://www.xjtalk.com/showthread.php?t=14767

[bjxj]

Thanks for the help guys, got my xj running good again. Did a refresh on the major ground wires at the oil dip stick tube, and cleaned out all the gunk from the c101 connector and these two things did the trick. My xj is back on the road and I am happy and relieved.