Stuttering V6

Hello All!
First let me say thanks for the information that has been shared by this forum!
I have a 99 3L Solara and about a week ago after lunch, it started stuttering like it was misfiring without throwing any codes (it ran fine on the way to work about 20 miles and it ran fine on the way to lunch about 4 miles.)
When the engine is running in closed loop there is no problem regardless of acceleration or RPM. Shortly after it warms up (temperature comes up and idle drops down) it starts hesitating and sounding like it is not firing on all cylinders at idle, any accleration and any speed including constant.
I replaced the plugs and wires. I put a timing light on each of the plug wires. While it is warming up all 3 have a consistant spark. After it has warmed up all 3 have approximately the same miss (say 10 consistant flashes then a pause for about 2 counts then repeat.) I tried flushing the MAS with SeaFoam (I was out of TB cleaner), and cleaned the airfilter. That had no effect.
Even though I never recieved a warning light I hooked up the reader and found no codes stored on the ECU. I performed a forum search and am going to try cleaning the battery terminals. Not that I think that will fix the problem but it couldn't hurt. Thank you for your assistance!