I have similar symptoms.
Right now I think it's my TPS - so far I was unable to
remove the screws to check it out.
About fuel filter: definitely worth replace it quite often
(10-15k) since Contours tend to be picky on fuel filter and
pump, BUT when I had fuel pump problems it caused bad idle,
power loss and even pinging, but no bucking.
Bucking should be something momentary/intermittent problem
and a fuel system degradation is not like that (usually).
T.
