So my jeep wont always start right away and when it starts it idles a little high until it warms up then it starts to misfire and almost die. I unplugged the MAP sensor when it was going to die and it seemed to make it better. Would this be a bad map sensor or something else?

 

Any codes? Need info on Jeep as well. Help us help you.

 

Sorry. 98 cherokee with the 4.0 and no codes

 

Define "idles a little high". I would start by checking all of your vacuum lines and manifolds for vacuum leaks. Usually idling high can be traced back to a vacuum leak or a bad IAC. The MAP sensor measures manifold pressure so the fact that you got it to possibly run a little better when it's unhooked may also point to a vacuum leak as then the computer has no manifold pressure data to map with so it has to use a default map stored in the computer as a kind of limp mode.

Once you've determined you have no vacuum leaks then we can move on to testing sensors.

 

I would also agree with this - check vacuum lines first, there's a good chance there's one loose or cracked (I used to have an old Mazda that would do something similar - turns out my actual air intake was cracked. A little duct tape and she ran fine! )

 

Would a vaccuum leak cause it to misfire and then die?

 

It can yes.

 

The rubber pieces can dry out and split over time, so take a real good look at those. Give them a little squeeze. If you see cracks or splitting, replace. Speaking of the MAP, there is a small rubber elbow underneath it that is easily overlooked.

 

A smoke tester can be worth it's weight in gold on our older Jeeps. It really helps track down even small vacuum leaks. You can build your own for 50 or 60 dollars or buy one off of ebay for about 80 premade.