I posted this in a different thread, but thought you guys might benefit from it.
I finally decided to drop off the car to my indy for a valve adjustment. He has a very interesting way of diagnosing if the valves need adjustments or not (he does not have a scanner to read the MAP voltage). He says typically, the manifold pressure is a vacuum at idle. He has noticed that if the vacuum is less than 20psi, the engine needs some attention. Mine registered at 15psi, so he went forward with the valve adjustment. He said almost all of my exhaust valves were tight. Intake were fine. After the valve adjustment, my manifold pressure reads 22psi, so he feels confident my problem will be gone. So only time will tell.
It's been a couple of days and my wife says the car feels smoother with no cold hesitation and so far so good. My indy only charged me $155 for the valve adjustment so for cars that have less than 105K miles, I would actually recommend a valve adjustment before doing the "easy" stuff since plugs and coils are pretty expensive.
Once again, my car is a 2006 with 78K miles. Codes that were present were P0300-306 and P0175.