I have an '88 Cherokee Laredo 4.0, auto. If you are standing in front of the jeep, looking at the engine, look at the back of the air box at the vacuum lines. There are 2 small ones that plug into metal nipples, side by side. The one on YOUR left run to the vacuum harness, the comes out and hooks to a metal thing almost underneath the harness. I have had issues with the jeep stumbling at startup. After replacing 50-11 dozen things, I also notice that the aforementioned vacuum line had softened up and started deteriorating on the airbox side. At startup, the hose would collapse. Could this be the cause of my problems? I have already cleaned and regapped the plugs, cleaned and inspected the distributor and rotor button, cleaned the throttle body, and replaced the fuel and air filters. Thanks in advance for any and all help.

 

I'm not sure about pre-'97 models but I will say those vacuum lines get clogged over time with sludge. I started seeing HVAC duct control issues (they're vacuum operated) which prompt me to inspect mine. I had to replace a lot of the factory vacuum lines and used an air compressor to blow out the plastic "hard" lines.

If you're worried about an atmospheric leak, just spray carb cleaner over a suspected area and see if it affects idle. You'll know there is an issue if it stumbles.

 

TY, will try that when I get home and update.

 

Used the carb cleaner on every vacuum line I could find. couldn't find anything wrong. Have heard that these old Jeeps don't like the newer plugs, like the Bosch with the titanium core. The ones that are in it are the Bosch Titaniums or Platinums. Think I am gonna go back with the Champion RFN14LYs and see if it helps. Think its something to do with it being more compatible with the copper cores. Low technology at its finest.

 

update... I went to tinker with it and decided ti
unplug each injector to narrow down which
cylinder was missing. I noticed that the injectors
would rotate at the point where they plugged into
the fuel rail. I also noticed that as they rotated fuel
was bubbling out of 3 of them. Guess its time to hit the pick 'n pull to get the Mustang injectors, right?

 

Time to get replacement injectors. Rotating on the O-rings is normal. Leaking injector bodies are not tolerable.

Good call on the plugs. How about cap, rotor and wires?

 

the wires, cap and rotor are a-ok. Gonna do the plugs and either the 5.0 injectors or just new o-rings for the one I have and see.

 

Was fuel bubbling out the injector bodies or from the upper o-ring at teh fuel rail? FWIW, those original injectors aren't good t keep in there. www.precisionautoinjectors.com has complete sets priced reasonably and they are 4 holers.

 

I replaced the o-rings and plugs. Still have the miss. Gonna throw some seafoam at it tmw and see what happens.