Stalling at traffic lights/stop signs
 

I have a 2008 Pacifica Touring with the 4.0L engine. After a couple misfires two weeks ago, I decided to check the plugs. I bought the car with 78K miles about 4 years ago, and now its at almost 160K, and I had never changed the plugs. I didn't start into the job until late at night, and as some of you probably know, you have to pull the intake cover off, pull the boot coils, and you need a pretty long extension to get down to where the plugs are. When I pulled them out, they all were enormously warn away - both the center electrode and the ground electrode were massively eroded - I wouldn't be suprised if it was over .200" on the gap. In my hurry to get the job done, I didn't check the gaps on the new Champion Platinunm Plugs that I put in. Well, all my misfires went away, but shortly after this work, my Pacifica has started stalling at traffic lights and stop signs. No idiot lights come on - it just quietly stalls. Is there any chance its too small of a gap on the replacement plugs?
I have also read that theIr is a valve that need to release the transmission from overdrive that sometimes goes bad, and when the rpms get too low in that high gear, the engine stalls. The stalling problem seems worse when the AC is running, and another weird thing is that it seems to happen less if I run 93 octane premium.

Any thoughts or suggestions appreciated.

Thanks.

Haste makes waste....When running, does it run smoothly? At your miles, have you ever cleaned the throttle body or Idle Air Control solenoid(IAC)? How about fuel system cleaner in the tank? Sure you hooked back up ALL wire connections and hoses?

OK - thanks for some suggested additional things to try.