I've noticed recently that when I'm idling (2004 Ranger 4.0; 7,300 miles), either at a light or while in park, there is a perceptible irregularity to the engine with very slight shudders that can be felt. I have no idea if this is a new problem or if it has always been there. The dealer reprogrammed the PCM soon after I bought it last year owing to excessive engine knock when going uphill or accelerating--took care of that problem completely.

Any ideas?

Kent Kester