I want to thank every one for there email .... it helped me solve the problem... 97 Jeep Grand Cherokee 4.0
I did everything mentioned - the screw thing on the CPU did not help, replaced the CPU did not help, replaced the IAC sensor - did not help, crankcase sensor did not help,replaced the MAP sensor did not help but did run better but the jeep would run fine for about 3 or 4 min and then just stop.... dang this is getting way old times 10...
After messing with this problem for about 3 months I was over it... could not sell or trade in of the problem. Finally bought another car for my wife because I could not trust it any longer, just paid cash for a used 2006 Toyota (nice car), something I could trust for a while... The jeep would run but I never knew when it was going to quite on her. Anyway this gave me some time to think about it some..0
Two days later at work and the thought came to mind that maybe it was the ignition switch (I believe this was the Lord because I had been praying for weeks). Naaa could't be, doesn't make sense! I came home and did some research and sure enough I found out that not only could it be but it was good chance it was the problem all along. Long story short - I purchased the switch from advance store $64 and put it on myself.... Now she purrs like a kitten... problem solved!!!
Here is some info so you can check to see if you have the same problem.
Watch Your Dashboard Lights
In older cars, the natural wear and tear on a vehicle can lead to ignition switch failure. If the switch is failing, you will probably not hear any clicks from the main relay, which fires the ignition. Check the behavior of the dashboard lights if your vehicle stalls. Alternatively, when the key is first turned to position two, the oil light, brake light, charge light and other warning lights will not function. You can try a test to check the integrity of the ignition switch by turning the ignition key to the 'start' position. As soon as it tries to start let go of the key. Allow it to snap back to the 'run' position and note warning lights. If they go out as the switch snaps back then the switch is faulty.
After you purchase a new switch here is a video on how to change it out - http://www.youtube.com/watch?v=reonxApWkVU... took me a couple of hours actually 3... had to go to harbor freight to purchase a set of tamper proof torx bits.. because of the special screws holding on the switch to the steering column....
JIMH - Chesapeake Va 12/1/2012