you should double check your work.
I put about 120 miles on the car today in various trips. last night I painted the passenger side header (laaaate at night, as usual), bolted it on and went to bed.
This morning I jumped in, fired it up, drove it down the driveway - thinking to myself it sounds different, even though it's idling ok... shut it off, got out and realized I had left the passenger side spark plug wires unplugged .
Amazingly enough it managed to maintain idle speed just fine with 4 cylinders unplugged... the "oddness" of the sound was from the quiet passenger side.