1987 Jeep cherokee 4.0L sputtering?

Hi guys!, new member here with a very odd problem that’s been haunting me the past month…

So, the story goes, I have a 1987 Jeep cherokee cheif with 316,000kms. It has a Non H.O 4.0L or the “Renix” if your experienced around older cherokees and its a 5 speed. I bought this little gem as a graduation gift for myself at the beginning of summer, which i used all summer to go back and fourth to my job every week which is a lengthy 400km drive!

It never gave me any problems, minus getting hot going up the steep mountains, but it was later found out that i had half a radiator :whistle: So I changed it with a good one from a donor jeep. That worked well up until about a month ago,

I was driving home from a friends and all of a sudden without any warning it just started running like garbage… sputtering, misfiring really bad,and wouldent idle unless i had my foot down a bit.. so I pulled over and let it somewhat idle for a minute, which then it cleared up and was acting normal again. :S So I got home,and went to go do other things.

Later that evening I decided i wanted to go get a coffee, But when I got in my “trusty” old jeep and started it the engine shot up right to 3,000rpms! So I immediatly shut it down and opened the hood to check.

All the vacuum lines were on and after taking the intake tube off I could see the throttle plate was still closed, So I hopped onto cherokeefourm.com to get some insight, immediatly everyone started posting “Oh its your idle air control valve and throttle position sensor” So I went out and bought two new ones, put them on… and It went back to normal!… for about 2 minutes, then right back to 3,000rpms. So I decided to try another throttle body i had sitting around, I cleaned it put my sensors onto it and threw it on.. and it did the same thing

But I noticed if you plug off the Idle air control valve port the idle will drop down to about 900-1000rpms.

[Picture of current “band-aid” which is the peice of cloth jammed into the upper left opening]
[URL=http://s996.photobucket.com/user/kurama49/media/IMG_0842_zpsd7173c6a.jpg.html][IMG]http://i996.photobucket.com/albums/af86/kurama49/IMG_0842_zpsd7173c6a.jpg[/IMG][/URL]

So with the idle addressed enough so that i could take it for a drive, I noticed it had this weird sputter… as if the engine would die for half a second, then come back to life, this worsened the warmer the jeep was and the more open the throttle was and or if it was under a heavy load. So back to cherokeefourms, and I had everyone saying “try this, Try that, clean this, upgrade this,etc”

So me being a nitpick about used parts due to a little fire with my 78 chevy All of these parts are brand new that I’ve tryed [Minus the injectors cause i had a good set laying around] So that little list of everything I’ve tryed is:

Replaced the cap,rotor,plugs,coil,wires, and crank position sensor. To rule out everything with the ignition system.

Replaced the Fuel pump,fuel filter, and Replaced the injectors with ones from a H.O to rule out the fuel system

I’ve gone through all the wiring, cleaned every connector i could find, took apart every ground and cleaned them to bare metal and Made sure there are no vacuum leaks.

And for senors I’ve replaced the Idle air control valve, Throttle position senor, MAP sensor and the crank position sensor.

So at this point I’m stumped. I cant think of anything else, I actually took it to a garage, who had it there for 3 weeks… and simply called me saying “We give up on it, come get it out of our lot.” I even took it to the jeep dealer here in sydney, and the only thing they could suggest is changing the computer.

So please, if anyone else could give me some insight on this it would be amazing! And sorry for such a long first post, I wanted to give as much detail as I could.

and I’ll just leave a picture of the said jeep incase anyone is curious on how it looks.

[URL=http://s996.photobucket.com/user/kurama49/media/IMG_0877_zps7e60cf95.jpg.html][IMG]http://i996.photobucket.com/albums/af86/kurama49/IMG_0877_zps7e60cf95.jpg[/IMG][/URL]

And a short video link to a kind of not so good video to show the problem.
[URL=http://i996.photobucket.com/albums/af86/kurama49/IMG_0828_zps6384348f.mp4][IMG]http://i996.photobucket.com/albums/af86/kurama49/th_IMG_0828_zps6384348f.jpg[/IMG][/URL]