This might be a long one so buckle in. I got this jeep for 450$ after sitting for quite awhile and a couple little things here and there and BOOM she's running, not great but I was able to drive her home. From that point of first ignition as best I could tell, the #1 cylinder hasent fired. So I put about 300 miles on her over the course of a month or so and then when I was on my way home from work the 4.0 started stumbling, to the point with my foot floored I was revving up to 3-4K and crawling along. Got er home, and after some investigating discovered it was a couple bent push rods (#1,#5,#6) and after that she fired right up, running great short the #1 cylinder. So here we come a month and 200 miles later I'm taking my buddy to the doctor and on a hard, High revving turn I notice a pretty significant loss of power. When we got there I popped the hood and pulled a couple injector pig tails to confirm I had indeed lost 1,5,6 again. I crawled home, barley making it. Assuming it was rods again I take off the Valve cover to be greeted by 12 perfectly good push rods. So the next day (it was 2 Am mind you so not a lot of time passed) it wouldn't start at all. I started playing cat and mouse with the sensors replacing the CPS,pickup coil,IAC,temp sensors and the other sensor on the throttle body, coil. And cleaned the c101 and verified that my computer was good. So today, about a month and a half later, I got her running again but those problem cylinders still aren't running. Less than 200 miles on 4 hole injectors, pumps new. Getting great spark. Compressions all in the high 110 area. I did notice that my EGR doesn't kill it when depressed like it used to. On start up it revs to about 2.5k and holds at about 1100. As soon as I put it in gear it drops to 2-300. Any ideas?

 

Vacuum leak?

 

I wish. Spent a good 100$ redoing the old lines.

 

PM sent.

Have you checked your intake/exhaust for leaks? Vacuum lines aren't the only place to lose vacuum...

 

I do have a crack in my exhaust just past my header, you think that could be part of my problem? It doesn't leak a lot but it's defiantly there, I can't remember in what side, but it's close to an 02 sensor

 

I used to have a problem similar to yours. Part throttle stumble, and on turns it would stumble as well. It was stumping me. The last change I did before the problem went away was a new O2 sensor and vacuum harness from dorman. This was after messing with the fuel pump and other various sensors. My 87 XJ is running pretty good now.