I'm not sure how to describe this, but under acceleration, it seems like my truck runs a little unevenly, or is a little jerky, as I'm gaining speed. It doesn't seem to run up as smooth as it should/could. It's not as noticeable in normal acceleration (but I think it's there), but when I put the pedal down harder is when I feel it more. Today I replaced the plugs, wires, cap, and rotor, and it may be a little better, but it's not fixed.

Other info to help- it idles pretty smoothly, doesn't smoke, starts pretty easily, I don't ever hear any pinging or detonation. I paid Express Oil Change $60 for the intake/fuel system cleaning a week ago.

Any suggestions? Thanks. [/align]

 

It sounds as though one cylinder is misfiring, this will give you jerky feeling that you describe and become worse the harder you accelerate, with 200k miles I would run a compression check; it sounds like you have already addressed the obvious.
Make sure that all the cylnders read about the same, if you have one cylinder that reads much lower then you have found the bad one, if they all read good then you may have a bad intake manifold gasket, vacuum leak, stuck EGR etc.

 

If it were misfiring on a cylinder (and I'm hoping for a much cheaper problem, haha), would the plug from that cylinder show anything? When I replaced the plugs a couple had some tan powdery buildup. The closest picture I could match in the book I have said it might be from gas or oil additives. The others looked pretty normal as far as I could tell.