The usual suspects come to mind. Air and fuel filters can make a big difference. More information is definitely needed to isolate the problem, but you could also be looking at a boost leak or leaking up-pipes as well.
The fuel filter is right in the middle of your engine on the top. Should be able to lift your dust cover and simply unscrew the top of the filter and pull it out. It needs to be changed at least every 10,000 miles. It will get nasty dirty and slow performance down and worse.
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