Hi, Please, Any ideas?
I have a 99 Cherokee 4.0 with 186,000. I notice when i am sitting at a light that I have a slight "wobble" or miss every 20 seconds.
I have taken it in to two mechanics so far, they have put it on the computer and nothing comes up, all is good. I stopped at a place yesterday to pick their brain and the guy said it could be a cam starting to go and he said 4.0's are notorious for cracked heads from pulling trailers ect. HE said it would cost around $1800.00 to fix if it is. Is that reasonable? I just lost my job. Any help would be appreciated! Thanks

double post

First off, I would consider not going back to that last mechanic. What he said makes no sense.

The 00-01 has a cylinder head that is a little more susceptible to cracking, but you have a 99 and the head on yours is very solid.

And why he would suspect the cylinder head without a solid diagnosis of your problem is beyond me. Did he perform any tests? You don't just replace a cylinder head on a hunch....!!!

When you said that two technicians put it on their computer, do you mean they used a hand held unit to check for codes? Or did they actually put it on an "engine analyzer", which actually might be a good idea here.

I always start with reviewing basic tuneup hardware. Fresh Champion copper plugs gapped to .035, new plug wires, distributor cap and rotor. Until you have confidence in this hardware, you should not look for more complex causes. The importance of tuneup hardware cannot be overstated.

If you can't find the problem easily and you still don't have any codes, don't throw parts at this on a hunch. You actually would be well served and would probably end up with less out of your pocket to pay the piper and take it to a reputable shop that employs ASE Technicians and has the high end diagnostic equipment that will enable them to isolate your problem.

Thanks tjwalker,
He didn't say if it was a hand held computer or a high end diag.
I will start with new plugs, wires ect like you suggested first.
Really appreciate the help.