Dreaded p0300 code

[Humberto Alvarez]

I have a 2004 Sierra 4.3l v6 that has started to run pretty rough on idle like it wants to bog out, I noticed my exhaust tips black (don't know if that matters). I checked the codes and got the P0300 code random misfire. I have replaced the spark plugs and the spark plug wires as well as the ignition coil, distributor and the distributor cap. That did not seem to solve the problem and I've ran out of ideas. Anyone might have some insight on what it could be that is causing this P0300 code?

Edited May 18 by Humberto Alvarez

[richard wysong]

any other codes? How did the plugs look?

Edited May 18 by richard wysong

[Humberto Alvarez]

no other codes besides the ones to the catalytic converters sensors which It had on for a long time now and it never did anything. The Plugs looked in really good condition since I changed them almost 2 years ago and I had also changed the plug wires. 

[richard wysong]

try unplugging the MAF sensor and see if it smooths out, other than that look for a vacuum leak and check the compression and fuel pressure. if it has a fuel pressure regulator pull the vacuum hose and see if there is any sign of gas in it

[Humberto Alvarez]

Turned out it was the o2 sensors