Toyota Repair: 4Runner running rough, japanese model, 4runner

Question
I have a 93 4Runner, actually its a domestic Japanese model called a Surf.  It is an automatic V6, 3.0 liter, and is 4wd. I had it tuned up in November with new plugs and an air filter.  About a month later it started running rough.  Shaking at idle in gear, especially if you turn on the A/C. It clears up and runs well occasionally (everytime I take it to a mechanic!).  I've had the injectors cleaned and the timing checked.  the timing is good even when its shaking.  One guy suggested it might be the ignitor but I dont want to spend $200 on a hunch.  Have you heard of this happening to any one else? Any help is appreciated.
Thanks,
Dalton  

Answer
IT SOUNDS LIKE A MISFIRE!
START PULLING A WIRE ONE CYLINDER AT A TIME WITH THE ENGINE RUNNING..USING insulated pliers! THE ONE THAT DOES NOT CHANGE THE ROUGHNESS IS THE BAD CYLINDER. ONCE YOU HAVE THAT INFO YOU CAN GO FROM THERE. IT CAN BE A BAD WIRE(MOST LIKELY) WHEN WAS THE LAST TIME WOU HAVE THE WIRES CHANGED. DO THAT AND SEE. IF THAT DOES NOT WORK THEN IT'S THE IGNITOR FOR THAT CYLINDER. LET ME KNOW HOW U DO. PAUL P.