'91 Mazda 626 2.2 without turbo (Yeah, I wish.) has a rolling miss at> idle when in gear. It runs and idles smoothly at all other times, but> if the car is fully warmed up and I stop at a traffic light, it will> idle smoothly for about four or five seconds, then the idle will drop> and surge, drop and surge, from almost stalled to normal. If I put it> back into gear it will go right to normal (750 rpm) and stay there.>

I have looked for a vacuum leak, but there could still be one that I> missed. (Zillions of hoses.) I know that it could be just about> anything, but I wonder whether there's anything that jumps to mind as> a likley suspect. The manual talks about troubleshooting the various> controls using an "SST." Unless they mean the Concorde, I don't know> what that is. Do I need to corner the Snap-on man? How much will he> do me for?>

I realize that if you don't have all the diagnostic stuff, sometimes> the only available approach is to replace something to find out> whether that is the problem, but I don't really know where to start.> If you say, "Try replacing the throttle sensor." and I do and it> doesn't straighten it out, I am not going to be miffed. I just don't> have a best guess.>

Thanks for any help you can offer.>

Hamish