trouble code for egr valve Options

[morbiddelusions]

Hey i was just wondering my check engine light came on
and stays on the code it is giving is 7fast pause 1 flashes which
after running a search for engine codes the chart i found a link
to says 71 is the egr system
......
my question is that my celica a stock 94 st has a knocking sound
when it revs between 3,500and 4,000 rpm
sounds more like a acorn being shook inside a soda can other
than that and since the light came on it bucks lightly when cruising
it has no other problems engine wise that i can tell
could the egr system be causing this?
it has 225,000 miles if it is the original engine
the wierd part is if it was a bearing wouldn't there be
metal shavings in the oil from
what ever bearing is causing the sound?
also when i was under the hood revving it up it sounds like
the noise is coming from up top

thanks for any help.