Originally Posted by
Jack G
What's the mileage since the coils and plugs were changed? You could have a coil or a plug beginning to breakdown. Sitting in traffic could generate enough heat for a marginal coil to act up.
Change plugs if they have not been changed, change the wires as a matter of routine. I see no reason to change the coils as they seem to be very sturdy, they were not made by Lucas.
A vacuum leak would show up consistently I would say.
As mentioned before you should look at the air filters, but you said you had a service just recently so that should not be a problem.
Think seriously about any diagnosis a garage gives you, good luck.