Help!!!

I have a 1995 gmc sonoma. I am having a hard time locating my problem. I thought that i just needed new plugs (which I did, the old plugs were covered with carbon) but I have replaced them and still have the same problem. The engine is running extremely rough, there is now a popping or clicking sound coming from the engine, my gas mileage sucks, and whenever I shut off the engine I can smell fuel. Any ideas?
I was going to replace my fuel filter, but I don't know how to relieve the fuel pressure.
Thanx.

Which engine do you have?
Were the plugs on one side of the engine worse than the other?

You can relieve the pressure at the schrader valve on the fuel lines at the rear of the intake or you can just loosen the lines slowly when changing the filter and allow the pressure to bleed that way.

You have some of the symptoms of a leaking FPR you can check this thread for more info:
http://www.automotiveforums.com/vbulletin/showthread.php?t=462726

All the plugs are on the same side. I have a 2.2L 4cyl. The no. 4 plug was not as bad as the rest, but the other three were pretty bad.

the one and two plugs looked the worst.