2000 Pontiac Bonneville What could it be?

The car has same symptoms of classic, clogged fuel filter. How ever the rough running and lack of power is constant, rather it be at idle or during acceleration. I changed the fuel filter, plugs and wires, and ignition coils. Problem still exist. I had a fuel system pressure check and my numbers were off by a little bit. Right in the 43ish and the mechanic said it should be in the 68ish. Excuse me for not being automotively incline, ish representing the unit of measure that applies. Tech instantly says fuel filter and pump. Followed up by a cost of $450. My question is, can the problem be a simpler task, such as catalytic converter or a leak in a line or so on and so forth.