[mreid]

The plunger on a hydraulic lifter is retained by an internal c-clip. If those parts came from the lifter, it would mean that one cylinder will have a loose rocker arm as there is nothing to support the pushrod. The easiest way to check this is to remove the valve covers and inspect the rockers. This is a very easy check that you can do yourself and should be done before you remove the pan. Also, if this is the case, you would hear a very pronounced (noticable) ticking as you rev the engine. It also could be the cause of your acceleration issue, but it would be noisy.

If that is not the issue, your acceleration problem sounds like carb tuning to me.