At 64,000 miles I began noticing a shutter/sputter between 40-50mph. I changed the plugs, inspected the coil boots thoroughly(all clean), and tested the resistance of each COP with ohm meter(all checked ok). Replaced air and fuel filters.
An increase in performance is definitely noted!
But, the sputter still exists and has worsened. At low throttel, such as from a stop, 0-30 mph, the engine is hesistating big time and will smooth out after 30 mph. Yes, still notice the sputter at 40-50 as well.
I have to believe this problem is related at any speed.
Now that the problem is occurring at low speeds as well I question whetherthe trans fluid is the culprit.
STILL NO ENGINE CODES SET...
And because no codes are set I wonder if I am dealing with a fuel pump issue. A bad COP under a load or an EGR system failure would generate a code eventually I assumming...
Any help as always is greatly appreciated....You got me this far...

 

If it's a stutter, as in feels like it's not running on all cylinders, I would suspect a bad COP, because that's exactly what my problem was. But, mine threw codes that identified the bad coil. Without codes, it would be really hard to tell which one, if any, are bad.

I don't know much about how to test fuel pressure or EGR stuff, so I can't comment.

Good luck...