My buddy has a 200 xj 4.0l. I've been trying to sort out it's issues for a while now but I cant seem to come to a solution. when it's cold it runs pretty rough at startup and usually revs alot around 3000 rpms. His mother took it to a garage because the check engine light was on and he said it was a bad fuel injector and told her what error code. I don't remember the error code but the injectors all seem to be spraying fine. I was curious if anyone can provide any insite into these issues.

 

Try checking the 02 sensor generally it's the front one, i had the same problem except it was always rough and i was scared to go past 40 when i first got it because of that and i had the death wobble(which is fixed now woot ^_^). Just my two cents.

 

Had a problem similar to this on my 99 code was system lean not sure of the number...changed o2 sensor problem solved.