That's what I'm wondering is the problem with mine.

 

What would a bad map sensor do?

 

Would make it run crappy on all cylinders, not consistently on just one.

 

Is there a spacific part of the vacuum system I should check that could cause a misfire? I know a leak can cause a lean misfire. I'm just not the best with the vacuum system.

 

Plenum gasket.....

You could try just plugging off everything vacuum related, except the brakes.... and see if it made any difference.

 

You should have reset the pcm before you went any further. This will clear all codes. Old codes have been know to come back after the issue was resolved. Take the battery terminals off and touch them together. Put them back on and take it for a drive.

 

Would a vacuum leak cause it to run lean and have random misfires?

 

Yes, yes it would.

 

I did reset it. I'm really thinking I have a warped intake manifold. Hope the computer is not messed up.

 

Check your plenum first.