Hopefully someone can point me in the right direction...
Today on my way home from work, my GM developed a bad shudder/stumble on light acceleration, steady speed, and sometimes while sitting in gear at idle. If I put my foot into it, it clears up and seems to run fine. It also goes away if I put it in park or neutral. The "foghorn" sound from the airbox has also returned, and it almost seems as if it may be related to my shudder issue. I say this because the only time I noticed the shudder while sitting idle, was when the "foghorn" sound was happening. The spark plugs in the car only have around 5k miles on them, all 8 coils only have maybe 100 miles on them, the IAC was cleaned 2 weeks ago, and I'm not getting any CEL or codes. If anyone can point me in the right direction on where to start looking for a problem, I'd greatly appreciate it.