It still sounds to me like the injectors are faulty. I've found that they stick in the open position, causing one or more cylinders to run too rich at idle. Try unplugging 1 injector at a time while the engine is idling. Good injectors that are unplugged cause an immediate notable miss, while the faulty ones take a few seconds before the miss happens.

If you do find a faulty injector, bite the bullet and replace all the injectors. I've never replaced just 1 injector without the rest needing replacement shortly thereafter.