Rough Idle/Miss after valve cover gasket swap

[SeattleXJ]

1989 4.0L Auto

I had a bad oil leak from an old cracked and dried up valve cover gasket. I swaped in a new one and degreased the valve cover. After letting things cure over night I came out and started my Jeep. It idles extremely rough and there is a noticible miss at all rpms. It seems to be running rich... when I rev it up there is a heavy exhaust plume. I didn't unplug ANYTHING, I simply unbolted the valve cover, cleaned it put a new gasket on and bolted it back up. Any ideas?

 

[SeattleXJ]

I FIXED IT!

I started looking around a little closer. I got out the mulitmeter to test sensors... I get to the MAP and my dumb-ass had broken the vacuum line to the MAP sensor.

 

[Manuel]

Check to see if you broke any of the hoses going to the valve cover or any vacuum hoses near the cover that you may have moved while working on it.
It sounds like you may have a vacuum leak.
It could be a simple crack in the hose.
If it's an 89 and you've never replaced the hoses, I figure they may be hard and brittle. You may have cracked a hose.

This would cause the engine to run rich.

Hope this helps, good luck.

Manuel