I recently did an engine rebuild on my 98 xj. I was having a lot of trouble getting it started until today. I replaced injectors and used some throttle body cleaner and it finally fired up. It kept dying shortly after it started. After a day of cranking and starting it finally starts the first try and stays running but it still has a really rough idle to the point its shaking the whole jeep. The idle is even more rough when in drive coming to a stop. so I purchased a cheap scanner to try to narrow it down so I could stop throwing parts at it but it came up with no codes.. I was thinking its either the O2 sensors, IAC, MAP or possibly the TPS.. any thoughts?? I don't want to blow all my money on stupid sensors please help!

 

Have you tried driving it?
IAC doesn't cause an extremely rough idle in my experience, so you can rule that out.
Have you check spark plug gap?

 

You might want to recheck your firing order and/or making sure your distributor is indexed correctly.
just an opinion, not an expert...

 

Can be several things. Especially with engine been taken out. Is it drivable? What things have you checked yet?

Start simple by going over things like all connections including spark plug leads (check sequence on distributor), sensors also including CAM, connectors etc etc and make sure all grounds (you'll have 7 in your engine bay) are all good, clean and tight.

 

I drove it to the gas station about half mile down the road got out and let it idle while I put air in one of the tires and drove it back home and it didn't die I know my distributor is indexed right I have new wires and spark plugs I double checked the firing order multiple times I did not check sparkplug gap though...

 

Since checking sparkplugs is quick, I would suggest you give that a try.
If the engine is a lot smoother when driving, you might have a vaccuum leak.

 

Bingo. There are diagrams out on the Internet taken from Haynes and Chilton manuals which are WRONG. Your engine will run, but very badly. This is the first thing I would check.

This is why you are better off with NO manual than a Haynes or Chilton. Missing information is frustrating, but WRING information is even worse.


Here's the correct info from The Man, The Legend, The Cruiser.

 

****I had rough idle that was fixed with new spark plug wires. 95 cherokee. Pretty sure they had the originals on, 73,000 miles.

 

So I checked spark plug gap they are at .35 so all good there. I swapped out the IAC with a new one I checked for vacuume leaks and there were a couple suspect spots that I sealed with black RTV. Its still running pretty rough not sure if I found all the vacuume leaks if there are any. I also removed my throttle body and cleaned it really good and sealed it with the gasket and RTV. Anything else I could try besides the distributor? because I went over that multiple times and I know that thing is down to the gnats ***.