Heat causing engine problems?

[MJ is dead]

Here's a new one. While at the mickey d's drive up last night I noticed the engine sounded a little rough, so I turned the heat off to listen. It went away. Turn the heat back on and it sounds like crap again. Almost like its missing or misfiring.

 

Any ideas?

[-600JeepMJ]

:hmm: :dunno: look for a vacuum leak. I am guessing since you had your heat on when it happened and since the heat is vacuum controled it may be a good place to start looking for the problem