Drops into limp mode at idle

[sk8nmike]

2004 ranger 3.0l autotrans.

Sitting at a stop light is will start idling rough then drops into limp mode, I can drive for about 500 feet with it floored and it will start running right. I've replaced the mass air flow sensor and the throttle position sensor, plugs and wires. Common failure codes are misfire at start up, random misfire and cyl 4 misfire.

On a side note that might be related there are times when is has rough shifting...

 

[fr7]

It almost sounds like your coil pack is going out. I think mine is too since it's been randomly misfiring. Maybe someone here knows how to test coil packs..

 

[sk8nmike]

Update: Screen shot of error codes

I've attached a screen shot from OBDLink.

 

[sk8nmike]

Replaced the coil pack and trunk run ok for a few days, but now it's started acting up again. Any help?

 

[paulblr]

I no mechanic but its sounds like a timing issue. So my guess is to check your cmp closely. I'll link the page about it here.