Originally Posted by swartzentruber
To the OP, I've definitely noticed low torque at those RPMs, but never any stumbling. Sound like an issue. Has this been happening for a while? Sure you don't just have a bad tank of gas?
I first noticed the condition a few months ago. Spark plugs looked really bad, nothing else were found. The new plugs seem to have fixed the problem, but it is coming back after only 2-3 months.