I have about had it trying to figure out with my 96 xj sport. It idles real rough misfires badly after it been run for a bit and sometimes just shuts down... I have cleaned the IAC,MAP, replaced distributor cap, plug wires and plugs. I took it to a parts store to get coded it said it was misfireing cyl#1 and the map that what led me to clean it. It ran a tad smoother after but no fix. Im at a loss guys any thing else I should check?
Also sorry for the long post

 

pull the #1 injector conection and see what happens. either be the same or run rougher. could be a bad conection or bad injector.

 

Ok I will try that when I get home thanks

 

Or just move the injector to another cylinder and see if the misfire moves with it.

 

List the exact codes for the most accurate replies. With OBD, the devil is in the details.

1. Replace the MAP, cleaning won't cut it. And be darn sure that the vacuum line leading to the MAP sensor is pulling good vacuum and that it isn't leaking vacuum because of cracks on the end of the vacuum hose.

2. If it continues to code for cylinder #1, yes...swap the injector to see if the misfire code follows. Put a noid light inline to see if that injector is receiving a "pulse" from the computer. Without a pulse, you are not going to have fire in that hole. If you get stuck, run a compression test on all cylinders and see where cylinder 1 fits into that mix. Should be 120-150 psi, with no more than a 30 psi variation between cylinders.