Too intermittent and random, mifire would increase and be rather consistent I would think. But it is past time for a tune up, so...

 

The misfire usually shows up right after it shifts into overdrive under light throttle - around 40 mph or so. If you have more than 60k on the spark plugs it's due. If it still does it you may need one or more coils. A live scanner can detect misfires before they are bad enough to trip a CEL.

 

If it really is the converter clutch shuddering you can fix it without replacing the torque converter. Do a full fluid change with a good quality MERCON V fluid. That cures about 94% of the vehicles with shudder problems.

I think it is misfire, too.