Vibration/shudder from engine

[philobeddoe]

Under load, like going up a hill or just plain accelerating, I feel a vibrate/shudder coming from engine. I can also feel it in park when I give it gas. No matter how fast going down the road, if foot is off the gas it is very smooth. It is also smooth at idle.

I'm stumped! Plugs and wires were changed when I had valve seals done back in Sept. Could it still be a bad plug or firing order, I guess I would have noticed before then? Maybe a plug got bad since? Timing, hoses??

I'm stumped! Thanks for all help.